Possible to run CPU with no fan if you underclock it?

[derek odonell]

Just a general curiosity question. For non-gamers, current PCs are way more computing power than we need, we can easily do with half or less of the CPU's potential. I figured that if you underclocked the CPU to a quarter of its stock speed, and also reduced the CPU core temp to as low as is allowed (say 0.75 volts), it would result in a heat generation of barely 10% of the CPU at stock settings. Maybe you could deactivate the CPU with such low consumption and still the core temp would be within tolerable limits. This would make your PC way more silent. But I'll bet there are some built in mechanisms to impede the CPU from starting if it doesn't detect that the fan is running.

[Agent]

It used to be done in the older days, and certain chips now (such as some Atoms) are designed with this in mind.

It would be interesting to see how an underclocked / volted AM1 chip would be at this. I suspect quite well

[Hoonigan]

I think you would still need some kind of internal airflow, just to move air about a bit, but it would be do-able with a large heatsink.

[deFiniLoGy]

Well, you can indeed disable the Fan speed monitoring in the BIOs.

Then, if you have a large enough heatsink and installed it right (i.e. good thermal paste and uniform installation), then you will be ok to leave it at passive cooling. But then you will still need some airflow in the case.

[DanceswithUnix]

You can passively cool just about anything if you use a big enough heatsink: http://www.quietpc.com/fx70?gclid=Cj...jfehoCwxfw_wcB

But yeah, you want a fan *somewhere* in the system, or it starts getting very expensive.

[Bonebreaker777]

I run my PC with lowest FAN settings available (700RPM 12cm FANs) and no active cooling on the CPU.

The NAS I recently finished building (more of a home server that a NAS) got the same, but I demonstrated that a Celeron G1620 underclocked can run even without a heatsink, let alone a running FAN.

Personally I think you just need to have a specific budget in mind first and then decide about the purpose. Maybe it is ridiculous but the new home server is so silent I can hear the HDDs humming in idle (WD Purple 3TB). I would say the most important part for making it silent should start with the PSU or power unit because usually you can't regulate them and neither can you modify the factory FAN. Need to find either one that is very quiet in idle or can turn off under low load (picoPSU+power brick, etc).

[DanceswithUnix]

Maybe it is ridiculous but the new home server is so silent I can hear the HDDs humming in idle (WD Purple 3TB).

Annoying that isn't it. My server makes a humming noise from the pair of hard drives, I'm sure it is a beat frequency between the two. A single drive is basically silent.

[CAT-THE-FIFTH]

Is the server in a case with soundproofing??

You can always get the sticky foam to deaden the sound of the HDDs.

[DanceswithUnix]

Is the server in a case with soundproofing??

You can always get the sticky foam to deaden the sound of the HDDs.

My case is an Antec Fusion with built in HDD decoupling rubber things. Hard drives are WD Red, which as I said seem silent on their own. To be fair they are pretty quiet as a pair, but I am really fussy about PC noise in the living room.

[CAT-THE-FIFTH]

My case is an Antec Fusion with built in HDD decoupling rubber things. Hard drives are WD Red, which as I said seem silent on their own. To be fair they are pretty quiet as a pair, but I am really fussy about PC noise in the living room.

You can get sticky acoustic foam - my main PC uses an aluminium SFF case and adding some of the foam made a noticeable difference.

[Bonebreaker777]

Annoying that isn't it. My server makes a humming noise from the pair of hard drives, I'm sure it is a beat frequency between the two. A single drive is basically silent.

More specifically, the HDDs can be heard only when I put my ear close. Yesterday during migration (from old Synology to new custom) even the case was opened and there was 4 HDDs working, after midnight I had to come close up to check if it was still working.

On the other hand it does depends on the HDDs. Like 5400RPM vs 10kRPM and such.

[scaryjim]

I've actually just modded my DAW by removing the fan from a stock AMD cooler, and adding a 140mm exhaust fan. CPU is a 45W Athlon X2 4050e, case is a tiny little 2U rack mount project box made of plastic, and the 140mm exhaust blows out of the top. Previously, without the exhaust fan and using the stock cooler normally, I was seeing CPU temps hitting 60C within 10 - 15 minutes of turning the computer on. With the new set up - de-fanned stock cooler + 140mm fan (it's an Antec tricool on medium speed setting) I haven't seen a CPU temp above 50C, and it tends to stay around 40.

Case airflow is everything. If you can get the hot air out of the case, even a cheap lump of Aluminium like the stock coolers AMD give away will do the job without a fan