Pulse Width Modulation EXPLAINED 

Knew the PWM thingy already , but luv getting re-schooled/refreshed on these topics (cause Iam old :p ) as SS makes these vids so interesting vs online reads or paperback.Thaaaanks Greg

I knew about PWM and how it worked, but dammit I learned something new. You got me again, Greg. Nice vid, as always.

I had a vague idea of what PWM fans were but this video gave me a better understanding.

FANTASTIC explanation, Greg. Your use of a guitar to explain the amplitude and attenuation was clever and incredibly helpful. One of my favorite videos of yours so far. It felt very much like an "Engineering Explained" but for computers rather than for cars/mechanical-engineering.

Thanks I was just talking about PWM with a colleague. Great explanation!!

Very nice explanation, I never really understood how the fans could be getting constant 12v yet be able to run at 25% speed but now that you explained it, it makes perfect sense, thanks!

Can't wait to watch, glad you keep making such nice content !

ESP/LTD love.

Excellent video. I literally just learned about PWM at university, but this still taught me a thing or two.

Surprised a video about fans is interesting.

The higher the ON TIME of a signal, the higher the UP TIME of the fan will be. The fan basically stops when the N TIME[ data bit = 1, on time] ends and tries to stop due to next bit being 0 i.e. OFF TIME but, the motion keeps it going and as the PWM waveform switches states in nanosecond scale, the state change of fans[ off-on-off-on-...] is NOT visible to us human eyes. GG, Electronics student here, the first tech channel I've seen who at least knows what he is dealing with and let's the community know it. A big thank you Greg sir, good wishes from India. :) *Science Studio, hence justified!

What a beautiful Eclipse :)

nice man, good informative video. Love to see this kind of content, I use and suggest your videos to people getting into PC building and videos like this make explaining things sooooo much easier.

So just one week after presenting my PWM circuit as my final project and getting a bad score, you upload this video...

Your guitar comparison was on point!

never stop making informative vids like these thanks man

Nice guitar dude. You think you would do more videos on instruments, amps, or pedals. I would love to see a Science Studio take on these

Damn that's one sexy guitar

I feel proud for learning... Arigato Sensei!

Thanks for the wonderful explanation! This is why I watch your content.

Gotta love seeing that gorgeous guitar.

Wish there was a love button instead of a like button.

Great video, just switched my cpu cooler over to PWM in bios. You make it fun to learn as well!

I'm using a retro Cooler Master ATC 200 case so the I definitely appreciate the PWM technology. Since my case only allows 80mm fans, letting them sync to my bios' fan curve to modulate their rpms makes it much nicer when I'm just casually using my desktop.

Great job breaking that down.

Perfect explanation, thanks! Personally I decided to go for the Silent Wings 3 DC fans though, as I found them for half the price of the PWM. Would’ve preferred the PWM, but I can’t go past a deal lol.

As always love the science. Thanks for the vid.

This video showed up in my subscription feed twice

love an engineer explaing things . !!

most of us here knew that already , but tutorials like this can help newb a lot 👍👍👍👍

Although I already knew the info Greg, really liked the whiteboard stuff. More please ☺️

Holy smokes.... You actually made a good video. Nice work.

Beautiful guitar. I don’t have any Les Paul shape guitars, only superstrat style (Ibanez RG320 from 2001, and a squier strat that I’ve modified).

Analogy: It's like a kids carousel. The adult puts energy to push it around in a circle, with the carousel spinning at a constant RPM with the adult pushing every so often to overcome friction losses... to spin faster the adult may push/pull just as hard but do it more often.

beautiful ESP. i'm ready for some shred vids

In addition, in the LED age and lighted fans, running lighted fans in varying dc mode, lights will change brightness accordingly. In pwm 12v are always there and lights will stay bright

Thanks for educating.

I'm more of a fender man myself but that guitar was very nice

Someone wants to show off his new "Ben" guitar...? Awesome piece, props to that special someone 😉

Thanks, Greg! Love the info!

Cool n quiet also affects my 3 pin case fans rpm. If i don't have it on, then they go max speed.

thank you for making this

You didn't explain WHY PWM control is better than DC control. DC fans can be adjusted almost as well as PWM fans, the low speed operation is just a minor bonus that PWM control gets, but it's absolutely not why they are used, and better. The reason PWM is better than DC control for fans is all in the power supply. Providing variable power to a fan by varing it's DC voltage requires another power supply, similar to a Vcore VRM.. a hell of alot simpler, it's typically a simple buck converter, but this is inherently less efficient than simply giving the fan 12V and the fan doing the work of regulating it's power draw (which is either on or off so no wasted power). This is why your PWM motherboard headers can easily take 2A current, if not more (the simply connect straight through to the 12V of the main PSU), but most DC controlled headers can only provide up to 1A safely. Above that and the buck converter built into the board will overheat, especially in the 50-80% region. This is the same principle as any mosfet consuming power - it consumes most power when switching between on and off, either fully on or fully off it doesn't consume much power at all, (and why your CPU draws almost no power when not switching) - but when switching has it's highest value of current*impedance, meaning the I*I*R power losses are highest. The mosfets in the buck converter will be in this state most when providing between 50-80% of their input voltage of 12V. Some well designed fan power supplies will sink the most power at full load, and be more efficient at lower voltages. Either way, with PWM all of this is negated, other than the much simpler and more efficient mosfet in the fan hub itself with far lower switching frequency (it only needs to switch typically once per 1/4 fan revolution if at all, so about 100 Hz) which is much less than a typical buck converter mosfet switching frequency in the DC-DC converter, which switch in the 300 KHz range. This is the only way to do DC to DC for power electronics, it's still a switched mode power supply and so ~85% efficient, but chopping it to AC, and back to DC is the only way. Using a linear step-down like a variable resistor or those resistors you can put on fan cables would be more like 50% efficient, so it has to contain switching mosfets, capacitors and inductors - again not needed for PWM, other than a much simpler more power efficient design that switches only when the fan needs to - for powering the coil for part of it's cycle. Sharing a PWM signal to control 10 PWM fans is easy, anyone with a soldering iron can make the connections, assuming powerful fans or water pumps etc.. - 5A draw at 12V, no problem, and nothing else needed other than the PWM signal from the CPU fan header, and 60W on the 12V rail of your main PSU (and routing 5A through the board or wires, however they are connected, which is no issue). Controlling 10 DC fans from a DC signal that can only provide 1A max (so can only be used as a signal not power supply), or using a PWM signal to modulate a buck converter to make 5-12V DC up to 60W - the only way to control those fans - means an actual 70W power supply that costs as much as 70W DC-DC converters cost, and dissipating 10W of heat from the extra power supply, and routing 6A to it from your PSU). This is why PWM control is better than DC control, and why if you deck out your system with fans, only a few can be DC controlled if your motherboard does DC control at all.

Great video as always Greg :)..Greetings from Italy

That was a great explanation. Thanks.

nice guitar there!

thx for explaining Greg-san 😁👍

Dayum dat LTD guitar

Nice video. Some fans are already so silent you won't hear them even in DC mode much, especially with low TDP CPUs. Still don't see the killer advantage in PWM apart from extremely low RPMs (versus not running at all).

ESP LTD EC...256? Edit: ooo the 256 has the 12 fret model inlay, the Ec-1000 doesn't. Great sounding guitar nonetheless.

Yeah bro! Super simple..! Thanks for the explanation! ❤️ BTW what’s your chair...it looks super nice!

Keep it up S.S

Let's see you play that Axe!

I'm getting bad flashbacks from my microprocessors 2 course from last semester. That shit literally gave me ptsd

That’s so funny, we are using PWMs for our robot using arduinos in one of my engineering classes

Great video

good boi, you won a damn cookie

Great video, thanks for the explanation! Love the guitar! What brand/model is it?

Nice ESP/LTD! Videos about guitars would be great as well.. :D

3 pin version of same fan can be better as the 4 pin at same speed. Btw, I can recommend the Noiseblocker NB-eLoop B12-1 and B12-2, which I use since 4 years. The B12-PS version is the pwm version, but the 3 pin versions are somewhat better.

love the animations

Eclipse is love

you should make a video or two on your guitars. I'd watch that tbh.

Nice eclipse man!

not sure if anyone mentioned this before but you look like the actor (Joseph Fiennes) from enemy at the gate haha

that is a nice guitar

So, you have a use for that Marshall stack... Favorite Metal band?

Where u live at man? Love the way you explain things and wish I could intern or work for you lol

Would love to hear some tones out of that ESP.

holy christ, that les paul is georgous!

so basicly, every fan has PWM if you connect it to a 4 pin on the motherboard? regardless of the fan if it is a cheaper or more expensive one?

Since you like Be Quiet Fans (I love them) is there a reason to buy the 3 pin variants over the 4 pin PWM? On New Egg the 3 pin and 4 pin PWM ones are always the same price (unless there is a special sale) With those fans I can't see a reason to ever buy the 3 pin variant unless its a special sale.

If I set my fans to spin at their lowest possible speed, will they be generating enough airflow or are they just overcoming internal friction and maybe just stirring up the air instead of pushing air through?

Should totally make a guitar video

Anything's a better alternative to its DC counterpart! Ayy!

Ah science... Good stuff

pwm is also on keyboards lights and monitors backlights, there is where it makes the most damage, creating flicker. most monitors are flicker free now, its in the spec sheet. keyboard however is still in the dark ages and dont state it.

More guitar videos!

How about making a cover in your next video Greg ? :P

Love your videos bro.

Guitar vid? Looks like an LTD or ESP. Do you play?

Hello people! I wanna ask you guys something. I wanna hook up a server fan, which is about 6000 RPM and draws about 3A of current, to my desktop PC. So my question is; can I draw the power directly from the power supply, where there is no shortage of current and no risk of damaging the motherboard traces due to excessive amount of power drawn by those fans, and connect the PWM and RPM wires to the designated pins on the motherboard? Has any of you ever done such thing before? Am I missing anything? Please let me know. Thank you!

But greg, would it be possible to add somekind of resistor ( between the fan connector and mobo pins) that reduces the output for the fan to decrease the RPM? We can regulate lightbulbs doing something similar so why not fans? One could potentially buy a set of fans and test them with a fancy science-lab powersupply to answer the question that is: how much voltage do i need to apply for the best airflow/noise ratio?

Hi. I want to test PWM fan with power supply, (+ and gnd), is it possible? if it is, how I connect two pins to the four pins of the PWM? Thanks!

Still waiting on a dyson vid

What's your opinion of an i7 3770 with a descent dedicated graphics card for a budget gamer?

i went to sc.st excited to see if you got a 2 letter domain in a 2 letter extension but it was a hair loss site.

I still like DC fans for one reason and one reason only. DC fans can be turned completely off so they don't spin at all. I have yet to find a morhervoard that can turn a fan off with pwm while many motherboards I have used can turn a fan off in dc mode.

I dun lurnd sumthin

I believe the pulse width and duty cycle is a weird way the describe it. The longer the pulse the higher the voltage and vis versa. This is just a VFD since computers are dc. (You know this I know.) now I didn't know about how the fans had the 4th pin. But if you have 12v to the fan and PWM. how? Since RPM = (v * Frequency) / # of poles in the motor. Is the drive on the fan or in the mother board? You won't need the 12v if you have the PWM pin. I'm missing something I'm sure. I'm half awake.

Ok question, if im wanting to connect 3 pwm fans of different sizes, a 200mm and 2 80mm, 200 being intake and 80's being exhaust, but only have 1 pwm header on mobo, can i use a pwm fan hub and safely run all the fans? If im understanding right pwm % based, so the 80mm will run at 75% of its rpms and the 200 would do the same? But theyd all run the same % but not same rpm since its a single header?

if theres a fan option in our bios AUTO/PWM, which one better ? and whats the different..

Remembered me of Chris Cornell's Les Paul

What pair of headphones are in the background?

23khz and what is volt in pwm blue wire ?

So this is why my cpu fan get louder than quieter by itself and it's a normal thing right ?

could you explain it using a distortion pedal next time?

Which software can controls the duty cycle?

So should I set my pc fans into Pwm or DC which is better

One more thing added to my knowledge ths mane