I did like this video and it gave me some ideas for my situation. Question for you though. I just built a pc with the Cooler Master H500m on the ASUS Crosshair VIII Hero (Wifi) mobo. The case has 2 200mm DC fans that turn on and off on silent mode like you were talking about. I was thinking of replacing them but now I'm wondering if there's a controller that can treat them like pwm and also make them visible in Fan Xpert 4. Any thoughts on that? Also, why does it seem like 200mm fans don't really come PWM except for Thermaltake but those have a proprietary connector that isn't just a regular PWM fan connector? Confusing stuff... Anyways, appreciate any help you could provide. Thanks!
Some server fans are 4 pin with some of the pins wired a little differently. I've completely forgotten the "standard" they use. I think it was just an annoying OEM rewiring. I was (about 10 or 15 years ago) able to re-pin the server fan to work with out issue on a standard pc motherboard. It was a nice fast dangerous delta fan from memory :D
@@tamaica7770 Stepping up and down voltages is rather easy to do. Stepping up and down current involves more work and other various reasons. More current = more heat for example.
skillet pan heat depends on P=IV. Lets say the fan can work at 6V, and mobo gives it current to operate. Increase current, increase the speed of fan. just not sure how they decided to choose V instead of I. maybe for safety?
4 ปีที่แล้ว +174
Finally - someone explaining it in a way that can be understood
I love how thorough you are about this subject and that everything mentioned is relevant and on track. The only thing I don't like is there is no discussion about the 4 pin molex connector fan type.
Damm! This man is unbelievable! I just wish I had known this channel before. Of the dozens of computer channels I know, this one is by far the best. What a fantastic teaching method! he doesn't need edits, animations or a ton of fancy equipment to perfectly explain a subject. That's talent! Thank you!
Voltage control uses resistance to lower the tension, therefore as a result it consumes more power due to the loss of energy as a form of heat; this makes PWM a power saver. I really liked your channel right away after watching a couple of videos because obviously it is not made for showing off but for teaching purposes, “not too many infos + accuracy at its best = subscribe”. Thank you.
- 3 Pin regulates through the amount of "juice" it sends to the fan. The more power the faster the fan spins. - 4 Pin regulates through timings, for how long the fan is on on end. Pretty simple. Can sum it up in two paragraphs. Great video, well done.
Well done on the growth of your channel and thanks for a brilliant explanation, I just got really nice be quiet case with 3x3pin fans and 2x 4 pin fans, I was a tad disappointed but eh still very cool, now I know that I can use them together reasonably, maybe not as 'cool' as 5x4pins but I think I can live with it for now, AUTO sounds really useful! ;D
Brilliant explanation, this is so useful in understanding how car radiator fans work and when your ac doesnt work with the fan going into full speed mode!
Realy nice video. I've enjoyed it a lot. Few time ago i've to buy a new processor fan because mine have burned after 6 years of use. I almost bought the 3 pin fan but after some internet research i discovered that processors use pwm (4 pin) fans. Then i bought the right fan for my processor and i am still waiting for it to come. Thanks for nice content. Regards. Rodrigo.
Nice visual of "pulse width modulation".............. hope folks appreciate the lesson!....................... Nicely done!........................... AJ
I just got back into building PCs again since 2002. This was a great video for clearing some confusion I have with my case fans in my new PC. Thank you.
I didn't know whether the fan was driven by the power of PWM signal or not, but now I see the maximum voltage of the PWM line only goes up to about half a volt, so my question is answered. This video is exactly what I was looking for. The power if provided by the 12-volt line and the PWM acts as a sort of relay that switches the 12 volts on and off. Thanks for the video.
THANK YOU! I bought 2 new fans for an older pc and I did not realize until today that I have 3 pin fans while the sockets on the motherboard are 4 pins. So I was sad that I must send back and buy new ones. You are a lifesaver and your explanations are amazing and easy to understand.
Video is fantastic, these are found on central heating appliances too, which now have modulating fans and pumps which work via a PWM signal from PCB. Normally heating engineers don't carry oscilloscopes, even cheap ones, so we are reduced to using Hz on a multi-meter.
Another beauty of PWM control: I'm a model train enthusiast. My DC trains can run on straight DC or PWM, but using PWM allows the lighting to remain at full brightness, and the sound function at full volume, at any speed. The full voltage is always available for a fraction of the time and is used to charge capacitors to power the accessories. Wall warts / power adapters can be made without heavy, expensive copper windings if they use PWM.
He is right all about what was said about how frequency works. We don't usually say times per second though. But more of how many cycles per second that the pulses are being made. "Cycles per second" or "pulses per second" sounds more straightforward instead of "times per second." Other than that, this is still one of the best educational video for people who would like to learn a little more about their computer fans and learn the differences between DC and PWM.
Duty cycle is still correct. even voltage controlled fans are controlled over a PWM dutycycle on the 12V rail. The fact that a motor is an inductor flattens the 12v-0v difference and averages it out to a voltage between the two values. with an oscilloscope you'd be able to see, that the line in fact has 12V peak and just switches on and of rapidly.
There is probably a capacitor also on the power rail which will average out the voltage so you will probably not see the full 12-to-zero volt swing on the line using a scope. But I agree that the voltage is most probably varied using PWM even for a 3-pin fan.
A few years ago I designed an AtTiny85 based DIY fan controller, and checking the tach in DC mode was a royal pain, because in the off/low part of the duty cycle, there was no power for the tach signal, so I had to run a burst of 100% DC (pulse stretching) every time I wanted to check the time between two tach pulses, which led to audible noise, especially at low RPMs. With a capacitor between the 12V and GND maybe the voltage would be flat enough to get a readable tach signal even in the off part. OTOH, the capacitor would cause the circuit to draw more current in the on part as the capacitor was refilled, and for the same reason it would also make the fan run faster at lower duty cycles because the average current would be higher, making speed control more difficult and unpredictable at low duty cycles. Unless I somehow found a way to feed the fan a PWM signal not between 0V and 12V, but between 5V and 12V, so that the tach (hopefully) always stayed readable with 5V logic. But then again, that would prevent the fan from spinning down below around 40%. (Hey, did I just stumble upon the reason for that particular limit in the BIOS?) Nah. My conclusion remains, 3 pin fans suck for speed control.
An excellent video, I just want to add a note, not all motherboard manufacturers are so restrictive like ASUS about the DC fan control, some allow to set the voltage down until the fans stop, even in DC mode. I have four 200mm Cooler Master fans, and the difference between 50% and 60% is VERY audible, in an ASUS motherboard the sound is really annoying at 60% but in my new motherboard I can set the voltage I want in the BIOS, if I remember correctly, I have the fans at 6 or 7 volts at the beginning of “the curve” and the sound difference is really big. It’s a shame that ASUS don’t give the user full control of the fans… That was why I change brand. Still, I really think that this was the best video I’ve watched on the subject, congratulations to the guy with the cool beard.
Great explain. One video per year watched entirely. I'm serious. I'm going to change my case and wanted to know about the exact difference between those two and I got it. That was really helpful. I watched this for future to what should I choose when I would like to buy two fans for maybe new case. Maybe it will not be necessary. I don't also comment too much videos and give thumbs up but there I should for giving 1:1 all knowledge about fans. Keep it going!
Thanks very helpful. Just subscribed. In my new build, currently a work in progress, I decided to use all PWM fans having just switched the original Silverstone 3 pin 180mm case fans for PWM equivalents - also ex Silverstone in a FT02 case. All other fans will be Noctua - I'm awaiting delivery of a new CPU cooler to finalise. Hoping to make it quiet as well as very capable.
Thank you! I've been hunting long and hard for PWM fans what will accept 0 duty cycle = 0 rpm and finding none of them wanting to claim less than 200rpm. That's fine, but I want them to STOP completely. Buying fans that clearly supported 0rpm or 0db mode seemed like it could cost me two hundred quid/dollars. Understanding that the DC fans, given the motherboard allows it (Crosshair Hero), WILL allow me to STOP "secondary" fans. Fans that provide filtered intake air for exhaust radiators, for example. I don't mind the main radiator fans being PWM doing 200rpm and not stopping, they are pretty silent. However for these only on under high loads fans.... DC fans will work I don't see many use cases where you would want to run intake support fans at anything less than 50% anyway. As I have a collection of DC fans and DC fans are cheaper that could save me a lot of money, especially as I'm 90% sure the CH H8 supports DC fan "Fan OFF" mode and 0% voltage.
Oddly the Alphacool rad fans are DC. Their label says 0-2500RPM. It will be interesting to see what their minimum stable speed is. I also have a box of fractal design DC fans I can test.
Also, note... The CPU fan headers are different. CPU FAN, OPT, PUMP and AIO_PUMP are all guarded to not go to 0 (PWM or DC). The CH H8 limits these to 40% minimum. This is where good quality PWM fans are king. They will adapt to the 40% minimum and be silent and slow at that, higher than normal limit on PWM. Chassis fans and aux fans will accept 0% and "Fan Off" states... at least on the CH.
TLDR warning. :) Your oscilloscope may not be the issue... Setting the fan to a low value, it STILL needs enough power to run. The computer, at a lower duty-cycle, has to stay within an "operable cycle level". Your desires, by settings, are just a suggestion, ball-park, of what is a safe lower end, and a maximum higher-end. Some fans have an internal controller to assist with the desired signal too. So, even though the BIOS says go to 1%, the fans controller may have its own duty-cycle for the actual fans 1% desire. (So it doesn't stall. They monitor the hall-sensor to get the RPM and can sense when the fan has stalled, or is about to stall. Saving the fan from damage, due to USER or BIOS stupidity or failures. Like when someone tells a fan to be 1% duty, or the signal is lost from a PWM control-pin. That is usually a $10 fan vs a $20 fan. Relative to a $2-$5 Voltage-controlled fan.) Though, most normal fans can be controlled with a PWM controller. They just don't have the (on-board control wire). So you would just not be able to use BIOS to control the fans speed. Which is why they sell separate fan-speed controllers. Those can take the voltage-level, and turn the output into a PWM-12v signal to feed the fan power. At the end of the day, the reasoning of using PWM over Voltage-control, is for efficiency, control and longevity. Feeding a 12v pulse, for half the cycle, which is equal to a 6v load, will consume half the power/watts. It gives the motor the voltage it needs to "spin", where a solid 6v might not give the motor enough power to spin. Reducing the voltage, in essence, the motor is struggling to function, as it is TRYING to get to the top RPM, but it doesn't have enough power to. While a PWM pulse, the fan has adequate power to spin at the full RPM, but the fan loses power for a specified time-period, using momentum to sustain a slower speed-average. With the aid of capacitors and diodes to sustain the average power, in the power-outages. Resulting in a drop of AMPS, at a sustained voltage. As opposed to a drop of VOLTS, which results in raised AMPS being drawn, with a voltage-controlled setup. (Thus, lower wattage consumed.)
Great video mate. I was wondering why my 3-pin fan that's plugged to a 4-pin connector is not controllable, checked the bios and turns out its still in PWM mode on that particular fan header. Switched to DC and it finally works. Cheers!
My question is, with a PWM fan, is the actual motor coil attached to the fans internal controller still two wires? If so couldn't they just keep the 3 wire method and change the motherboards control to do the PWM directly? I'm guessing that the fan motor itself is more complicated, possibly with multiple windings or something similar and uses a dedicated motor driver to provide more granular control?
Main issue is that if you drive the fan by its 12v wire, your fan controller has to switch the load of the fan. But with a dedicated PWM wire, the fan controller just sends a digital signal, and the switching is done by the fan itself - so a big fan that pulls a lot of power won't overload the controller. Additionally, yes a brushless motor usually has four coils in it that need to be sequenced, so there will be a driver for that in the fan, as well as the speed sensor. These two chips may behave unpredictably if their 12v power supply is getting switched on and off at 23KHz. There were some very early PWM fan controllers, mostly custom jobs, that were designed to drive the 12v pin, and while I never used one they were known for causing an electronic humming noise from the fan.
Hi, I have purchased a fan 12 volt and 2.8 Amps it draws about 33 watt full speed but it is too much air and consumption. If connected with the motherboard the fan spins and then turn off every 3 seconds. Maybe the motherboard connector release 12 volt but not the amount of amps required? So if I lower the voltage with a potentiometer, should I be able to lower the fans speed? I have a module that gives all the energy I want so 12 volt 2.8 amps I would like to try with this module to a smoother speed and lower consumption. Any tips to how do that?? thanks
One little bit to add is that you can use a 4 pin fan on a 3 pin motherboard connector. The 4 pin fan just stays at 100% speed by default but by controlling the voltage it will slow down.
You explained it really well. Now I am in a problem with colour codes of wire. My old 3 wire fan had brown, red, and black colour wires, and my new 3 wire fan of same model and same company(ebmpapst) has red, white and blue colour, so how to connect this new fan? Can you help me get the solution
I did some work on kit (not a PC) which had PWM fans, when the supplier was changed out in production there was a heap of fan failures in use. Long story short, newer fans although supposed to be identical would not start at the low speeds in the same way the old ones did. The *fix* in software was to start the fans at I think 50% rather than say 20% then once they were running and the speed confirmed drop the level.
Absolutely awesome video....I have been working and building computers for 35 years I know about 3 pin and 4 pin PWM but I never knew exactly how it was doing it...never to old to learn. I do have a question though. Will the 3 pin last longer that a 4 pin fan because of the pulsing on and off? You know how computers are sending voltage on and off is the sure fire way to kill a electronic equipment.
If you liked this video, I demonstrate this in action on LEDs in this video here: th-cam.com/video/sPkRS2sLXh8/w-d-xo.html
I did like this video and it gave me some ideas for my situation. Question for you though. I just built a pc with the Cooler Master H500m on the ASUS Crosshair VIII Hero (Wifi) mobo. The case has 2 200mm DC fans that turn on and off on silent mode like you were talking about. I was thinking of replacing them but now I'm wondering if there's a controller that can treat them like pwm and also make them visible in Fan Xpert 4. Any thoughts on that? Also, why does it seem like 200mm fans don't really come PWM except for Thermaltake but those have a proprietary connector that isn't just a regular PWM fan connector? Confusing stuff... Anyways, appreciate any help you could provide. Thanks!
Some server fans are 4 pin with some of the pins wired a little differently. I've completely forgotten the "standard" they use. I think it was just an annoying OEM rewiring. I was (about 10 or 15 years ago) able to re-pin the server fan to work with out issue on a standard pc motherboard. It was a nice fast dangerous delta fan from memory :D
Nice explanation. So why they don’t control the DC fan via current?
@@tamaica7770 Stepping up and down voltages is rather easy to do. Stepping up and down current involves more work and other various reasons. More current = more heat for example.
skillet pan heat depends on P=IV. Lets say the fan can work at 6V, and mobo gives it current to operate. Increase current, increase the speed of fan. just not sure how they decided to choose V instead of I. maybe for safety?
Finally - someone explaining it in a way that can be understood
I love how thorough you are about this subject and that everything mentioned is relevant and on track. The only thing I don't like is there is no discussion about the 4 pin molex connector fan type.
A year on from making this video and still the best explanation on TH-cam I've seen 👏🏻
"My fan doesn't work."
"Have you tried turning it on and off again 25 000 times a second?"
😂
-"off and on". What you wrote is both an incorrect reference -*-AND-*- doesn't make sense.-
I'm a dope.
Understand clearly now why my TUF Gaming X570 MB has the "fan tuning" function that calibrates fan speeds. Appreciate the content.
Damm! This man is unbelievable! I just wish I had known this channel before. Of the dozens of computer channels I know, this one is by far the best. What a fantastic teaching method! he doesn't need edits, animations or a ton of fancy equipment to perfectly explain a subject. That's talent! Thank you!
agree
Voltage control uses resistance to lower the tension, therefore as a result it consumes more power due to the loss of energy as a form of heat; this makes PWM a power saver. I really liked your channel right away after watching a couple of videos because obviously it is not made for showing off but for teaching purposes, “not too many infos + accuracy at its best = subscribe”. Thank you.
There are few people who can articulate tech (and engineering) stuff like this so well and more importantly present it as well...good work!
- 3 Pin regulates through the amount of "juice" it sends to the fan. The more power the faster the fan spins.
- 4 Pin regulates through timings, for how long the fan is on on end.
Pretty simple. Can sum it up in two paragraphs.
Great video, well done.
Well done on the growth of your channel and thanks for a brilliant explanation, I just got really nice be quiet case with 3x3pin fans and 2x 4 pin fans, I was a tad disappointed but eh still very cool, now I know that I can use them together reasonably, maybe not as 'cool' as 5x4pins but I think I can live with it for now, AUTO sounds really useful! ;D
Brilliant explanation, this is so useful in understanding how car radiator fans work and when your ac doesnt work with the fan going into full speed mode!
Thank you for this video. It was well worth watching and easily understood. Terry from Australia. 11/05/2024
Interesting and very useful, thank you
Realy nice video. I've enjoyed it a lot. Few time ago i've to buy a new processor fan because mine have burned after 6 years of use. I almost bought the 3 pin fan but after some internet research i discovered that processors use pwm (4 pin) fans. Then i bought the right fan for my processor and i am still waiting for it to come. Thanks for nice content. Regards. Rodrigo.
Nice visual of "pulse width modulation".............. hope folks appreciate the lesson!....................... Nicely done!........................... AJ
Definitely this is the best PWM vs Dc explanation on TH-cam. Please keep up your great job!
I wasn gonna skip the video when i saw the length but hearing you explaining something is so interesting i watched the whole thing.
Your explanation and demonstration of voltage controlled fans versus PWM control was brilliant. Thank you.
I just got back into building PCs again since 2002. This was a great video for clearing some confusion I have with my case fans in my new PC. Thank you.
Absolutely perfectly explained!! If only all teachers in engineering colleges had this ability.
This is invaluable! You need a Patreon, I'd love to support your channel. Thanks!
I didn't know whether the fan was driven by the power of PWM signal or not, but now I see the maximum voltage of the PWM line only goes up to about half a volt, so my question is answered. This video is exactly what I was looking for. The power if provided by the 12-volt line and the PWM acts as a sort of relay that switches the 12 volts on and off. Thanks for the video.
I didn't understand the differences until now :) Thanks Graham
THANK YOU! I bought 2 new fans for an older pc and I did not realize until today that I have 3 pin fans while the sockets on the motherboard are 4 pins. So I was sad that I must send back and buy new ones. You are a lifesaver and your explanations are amazing and easy to understand.
been looking everywhere for that information and there it is explained clearly and succinctly. thank you for the great video sir!
Thanks for making this video. I learned a lot about these fans and their respective differences. Keep up the great informative work!
As others have stated, this is an excellent and underrated video.
It answered all my questions and more. Well done.
Video is fantastic, these are found on central heating appliances too, which now have modulating fans and pumps which work via a PWM signal from PCB. Normally heating engineers don't carry oscilloscopes, even cheap ones, so we are reduced to using Hz on a multi-meter.
Superior explanation AND illustration of the differences between PWM(4 pin) and 3 pin fan operation and logic.
Another beauty of PWM control: I'm a model train enthusiast. My DC trains can run on straight DC or PWM, but using PWM allows the lighting to remain at full brightness, and the sound function at full volume, at any speed. The full voltage is always available for a fraction of the time and is used to charge capacitors to power the accessories. Wall warts / power adapters can be made without heavy, expensive copper windings if they use PWM.
Good explanation and examples of the differences. Thanks very much.
Thank you for the best explanation of how DC and PWM fans work. Thank you for your hard work.
Man, this video explained much more than I anticipated. Great job!
some people are very good at explaining tech related topics, but they should call you "Master", best explanation ever, thanks alot.
Thanking you for a very well given insite into dc and pwm mode.
Underrated video... This deserves more views.
He is right all about what was said about how frequency works. We don't usually say times per second though. But more of how many cycles per second that the pulses are being made. "Cycles per second" or "pulses per second" sounds more straightforward instead of "times per second." Other than that, this is still one of the best educational video for people who would like to learn a little more about their computer fans and learn the differences between DC and PWM.
Excellent presentation. Thanks!
Absolutely BRILLIANT explanation of this. Thank you!
Great video. Clear and concise!
Unbelievably good explanation, thanks a lot!!! 😎
Great explanation. It really has shown how much more control de PWM fans have, thanks!
Duty cycle is still correct. even voltage controlled fans are controlled over a PWM dutycycle on the 12V rail. The fact that a motor is an inductor flattens the 12v-0v difference and averages it out to a voltage between the two values. with an oscilloscope you'd be able to see, that the line in fact has 12V peak and just switches on and of rapidly.
There is probably a capacitor also on the power rail which will average out the voltage so you will probably not see the full 12-to-zero volt swing on the line using a scope. But I agree that the voltage is most probably varied using PWM even for a 3-pin fan.
A few years ago I designed an AtTiny85 based DIY fan controller, and checking the tach in DC mode was a royal pain, because in the off/low part of the duty cycle, there was no power for the tach signal, so I had to run a burst of 100% DC (pulse stretching) every time I wanted to check the time between two tach pulses, which led to audible noise, especially at low RPMs. With a capacitor between the 12V and GND maybe the voltage would be flat enough to get a readable tach signal even in the off part. OTOH, the capacitor would cause the circuit to draw more current in the on part as the capacitor was refilled, and for the same reason it would also make the fan run faster at lower duty cycles because the average current would be higher, making speed control more difficult and unpredictable at low duty cycles. Unless I somehow found a way to feed the fan a PWM signal not between 0V and 12V, but between 5V and 12V, so that the tach (hopefully) always stayed readable with 5V logic. But then again, that would prevent the fan from spinning down below around 40%. (Hey, did I just stumble upon the reason for that particular limit in the BIOS?) Nah. My conclusion remains, 3 pin fans suck for speed control.
Great work. Fantastic explanation. This is an absolute gem of a video.
Sir: Thank you very much for such a clear concise explanation. I was able to share this video and the concept was understood perfectly. 👍
An excellent video, I just want to add a note, not all motherboard manufacturers are so restrictive like ASUS about the DC fan control, some allow to set the voltage down until the fans stop, even in DC mode. I have four 200mm Cooler Master fans, and the difference between 50% and 60% is VERY audible, in an ASUS motherboard the sound is really annoying at 60% but in my new motherboard I can set the voltage I want in the BIOS, if I remember correctly, I have the fans at 6 or 7 volts at the beginning of “the curve” and the sound difference is really big.
It’s a shame that ASUS don’t give the user full control of the fans… That was why I change brand.
Still, I really think that this was the best video I’ve watched on the subject, congratulations to the guy with the cool beard.
Thank you superb explanation. I now understand the difference of the pins in depth !!!
Another great video, very clear to understand and a useful guide when buying PC fans.
Great explain. One video per year watched entirely. I'm serious. I'm going to change my case and wanted to know about the exact difference between those two and I got it. That was really helpful. I watched this for future to what should I choose when I would like to buy two fans for maybe new case. Maybe it will not be necessary.
I don't also comment too much videos and give thumbs up but there I should for giving 1:1 all knowledge about fans.
Keep it going!
Thanks very helpful. Just subscribed. In my new build, currently a work in progress, I decided to use all PWM fans having just switched the original Silverstone 3 pin 180mm case fans for PWM equivalents - also ex Silverstone in a FT02 case. All other fans will be Noctua - I'm awaiting delivery of a new CPU cooler to finalise. Hoping to make it quiet as well as very capable.
Thank you for perfect explanation.
This has been really good Thank you Thank you......Keep up ......!
Excellent explanations, thank you very much :)
the most useful video about 3pin vs 4 pin fans
Thank you for a very informative video with no unnecessary fluff. Good info!! I gave you a thumbs up & subscribed.
Thank you! I've been hunting long and hard for PWM fans what will accept 0 duty cycle = 0 rpm and finding none of them wanting to claim less than 200rpm. That's fine, but I want them to STOP completely. Buying fans that clearly supported 0rpm or 0db mode seemed like it could cost me two hundred quid/dollars.
Understanding that the DC fans, given the motherboard allows it (Crosshair Hero), WILL allow me to STOP "secondary" fans. Fans that provide filtered intake air for exhaust radiators, for example. I don't mind the main radiator fans being PWM doing 200rpm and not stopping, they are pretty silent. However for these only on under high loads fans.... DC fans will work I don't see many use cases where you would want to run intake support fans at anything less than 50% anyway.
As I have a collection of DC fans and DC fans are cheaper that could save me a lot of money, especially as I'm 90% sure the CH H8 supports DC fan "Fan OFF" mode and 0% voltage.
Oddly the Alphacool rad fans are DC. Their label says 0-2500RPM. It will be interesting to see what their minimum stable speed is. I also have a box of fractal design DC fans I can test.
Also, note... The CPU fan headers are different. CPU FAN, OPT, PUMP and AIO_PUMP are all guarded to not go to 0 (PWM or DC). The CH H8 limits these to 40% minimum. This is where good quality PWM fans are king. They will adapt to the 40% minimum and be silent and slow at that, higher than normal limit on PWM. Chassis fans and aux fans will accept 0% and "Fan Off" states... at least on the CH.
Thank you on behalf of all mankind. Perfect explanation.
Just the answers I was looking for. Thanks
Fantastic, 3 pin 4 pin fans worried my if I connected it on mono wrong, now I know I can’t. Thank you.
This is the first video I have watched on this channel and I liked it. Therefore: Subscribed.
Great content. Subscribed and thanks for all the hard work.😀
TLDR warning. :)
Your oscilloscope may not be the issue... Setting the fan to a low value, it STILL needs enough power to run. The computer, at a lower duty-cycle, has to stay within an "operable cycle level". Your desires, by settings, are just a suggestion, ball-park, of what is a safe lower end, and a maximum higher-end. Some fans have an internal controller to assist with the desired signal too. So, even though the BIOS says go to 1%, the fans controller may have its own duty-cycle for the actual fans 1% desire. (So it doesn't stall. They monitor the hall-sensor to get the RPM and can sense when the fan has stalled, or is about to stall. Saving the fan from damage, due to USER or BIOS stupidity or failures. Like when someone tells a fan to be 1% duty, or the signal is lost from a PWM control-pin. That is usually a $10 fan vs a $20 fan. Relative to a $2-$5 Voltage-controlled fan.)
Though, most normal fans can be controlled with a PWM controller. They just don't have the (on-board control wire). So you would just not be able to use BIOS to control the fans speed. Which is why they sell separate fan-speed controllers. Those can take the voltage-level, and turn the output into a PWM-12v signal to feed the fan power.
At the end of the day, the reasoning of using PWM over Voltage-control, is for efficiency, control and longevity. Feeding a 12v pulse, for half the cycle, which is equal to a 6v load, will consume half the power/watts. It gives the motor the voltage it needs to "spin", where a solid 6v might not give the motor enough power to spin. Reducing the voltage, in essence, the motor is struggling to function, as it is TRYING to get to the top RPM, but it doesn't have enough power to. While a PWM pulse, the fan has adequate power to spin at the full RPM, but the fan loses power for a specified time-period, using momentum to sustain a slower speed-average. With the aid of capacitors and diodes to sustain the average power, in the power-outages. Resulting in a drop of AMPS, at a sustained voltage. As opposed to a drop of VOLTS, which results in raised AMPS being drawn, with a voltage-controlled setup. (Thus, lower wattage consumed.)
This has been really informative. I didn't even know PWM worked that way.
BEST VIDEO ON THIS TOPIC SO FAR
Very good explanation, thank you!
Great video mate. I was wondering why my 3-pin fan that's plugged to a 4-pin connector is not controllable, checked the bios and turns out its still in PWM mode on that particular fan header. Switched to DC and it finally works. Cheers!
You my friend are a life saver!!
Great respect!
Thx, very good explanation and visualization
The Asus motherboard does allow under 60% voltage but only if you run the automatic fan configuration first. It tests the RPM range of the fans.
My question is, with a PWM fan, is the actual motor coil attached to the fans internal controller still two wires?
If so couldn't they just keep the 3 wire method and change the motherboards control to do the PWM directly?
I'm guessing that the fan motor itself is more complicated, possibly with multiple windings or something similar and uses a dedicated motor driver to provide more granular control?
Main issue is that if you drive the fan by its 12v wire, your fan controller has to switch the load of the fan. But with a dedicated PWM wire, the fan controller just sends a digital signal, and the switching is done by the fan itself - so a big fan that pulls a lot of power won't overload the controller.
Additionally, yes a brushless motor usually has four coils in it that need to be sequenced, so there will be a driver for that in the fan, as well as the speed sensor. These two chips may behave unpredictably if their 12v power supply is getting switched on and off at 23KHz.
There were some very early PWM fan controllers, mostly custom jobs, that were designed to drive the 12v pin, and while I never used one they were known for causing an electronic humming noise from the fan.
Thank you for explaining this in a way I totally understood
Fantastic! Very good explanation 😃
Awesome man BEST video on the whole net
Very well presented, thanks.
This was an excellent explanation, thanks
Thank you for that explanation of 3 vs 4 pin fans, you made it quite clear.
Increadibly good explaination, thx!
Perfect, now I understand. Thanks
Exceptional video. Thank you for helping the average joe understand!
Brilliant explanation 👌
Hi, I have purchased a fan 12 volt and 2.8 Amps it draws about 33 watt full speed but it is too much air and consumption. If connected with the motherboard the fan spins and then turn off every 3 seconds. Maybe the motherboard connector release 12 volt but not the amount of amps required? So if I lower the voltage with a potentiometer, should I be able to lower the fans speed? I have a module that gives all the energy I want so 12 volt 2.8 amps I would like to try with this module to a smoother speed and lower consumption. Any tips to how do that?? thanks
You’re awesome. Thank you
Very good video. Thank you very much!
Amazing job explaining dude
Great video, thanks for the explanation!
One little bit to add is that you can use a 4 pin fan on a 3 pin motherboard connector. The 4 pin fan just stays at 100% speed by default but by controlling the voltage it will slow down.
Awesome demo, thanks !
You explained it really well. Now I am in a problem with colour codes of wire. My old 3 wire fan had brown, red, and black colour wires, and my new 3 wire fan of same model and same company(ebmpapst) has red, white and blue colour, so how to connect this new fan?
Can you help me get the solution
Great job busting the scope out to explain the difference.
Can I connect two wires + and - 12V DC to this 4pin PWM FAN???? PLZ TELL ME!!! THANKS U👍
Excellent clear explanation. Thanks a lot for this vid.
I have learned something new today, thank you
great expectation!
Hard disk Drive ,cpu , Motherboard, Case fans
Which of these components does connect directly to the power supply? Choose two
Really informative video, I'm curious what probes you use. Mine are really wide and hard to get into a small area like that
I did some work on kit (not a PC) which had PWM fans, when the supplier was changed out in production there was a heap of fan failures in use. Long story short, newer fans although supposed to be identical would not start at the low speeds in the same way the old ones did. The *fix* in software was to start the fans at I think 50% rather than say 20% then once they were running and the speed confirmed drop the level.
Excellent ... Well done ...
Absolutely awesome video....I have been working and building computers for 35 years I know about 3 pin and 4 pin PWM but I never knew exactly how it was doing it...never to old to learn. I do have a question though. Will the 3 pin last longer that a 4 pin fan because of the pulsing on and off? You know how computers are sending voltage on and off is the sure fire way to kill a electronic equipment.
Real information.If you can do more new videos.It's good for World.
Excellent video, really appreciated.