Passive CPU cooling

Deadly Ferret

Deadly Ferret

Deadly Ferret

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I've been happy with my computers for years, doing nothing more than adding storage over the last seven or eight years, so my knowledge has fallen way behind. (No games, no CAD, no demanding usage of any kind.)

I was just searching on the internet to see what the current state of things is with passive cooling of CPUs. First time I looked in to this for nearly a decade. I found several articles written circa 2022/2023 which gave me the impression that it's a dodo now/nothing new developed for several years. One of those 'recent' articles was recommending a passive cooler I've had gathering dust in my shed since about 2016, a big copper thing called NoFan CR-80EH good for processors up to 80TDW.

Does anybody know differerently please/are there newer better options? I'd like to build a new but basic machine for non-demanding office use, and would prefer it to be silent. A quick look on the CPU section of OcUK tells me it's probably going to be an AM4 socket option. Remarkably my old copper thing apparently fits that socket (according to a 2022 article) which didn't exist when it was made. I suppose the architecture is very similar. I do like making use of existing items, but I can't help thinking 'modern processor = modern cooler'... Also, I was trying to remember why I wasn't using this cooler which was probably bought for a 65TDW processor I have air cooled. I think either the installation process made me worry about damaging the CPU and I wimped out, or in the end I went through with it but was concerned about the temperature I was getting with it.
 
The main problem with modern CPUs is that while they might have a TDP of e.g. 65 watt, when they are fully loaded they can use massively more power and will overwhelm most passive coolers, while cooking the VRM if you don't have any airflow.

You'd likely need to stay with CPUs on the lower-end of things, like a 5600G or 12100 (you could configure the TDP down or turn the turbo off, though this may have an impact on responsiveness).

Personally, I wouldn't bother anymore, because with zero-rpm modes for PSUs and graphics and fans supporting PWM, most PCs are pretty easy to make nearly silent at idle and if you kill all the fan noise you have to worry about electrical noise (even SSDs can be annoying) and worry more about coil whine.

You could also look at mini-PCs like NUCs.
 
Thanks very much you've given me a lot of useful information and perspective there. The case should have a lot of airflow as I'm intending to use, if I can find one somewhere, an Aerocool Dream Box. I already have a couple of them on the go, and really like them. That said, it might be easier (and better, for the reasons you gave) to pivot towards 'mostly silent'.
 
Tetras has it right, the only way to have a tower completely silent and then avoid virtually inevitable electronic noise like coil whine, is to put the computer in a different room entirely or close it off somewhere. I've seen some pretty silly cases of people RMAing products for whine, and unless it's severe I'm not sure I really agree with it :P.

Oversize your coolers (mostly to get a bigger fan on them) and then fan controlling the fans to an rpm you find pleasant / quiet enough to your ears, that's the best bet :).

I still remember a laptop I once had that didn't turn the fans on until required, but I could always hear an electronic whine whenever I moved the mouse cursor around the screen. It was very quiet, but so irritating when I was in a quiet enough place to hear it.
 
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Agree with the above but I also wouldn't over think it.
If you use decent fans they realy don't make any noise to speak of at low loads.
Case in point, I'm fully air cooled with decent cpu cooler and decent case fans... And at 'idle' or pretty much idle... Also a PSU and GPU with a zero RPM fan capability at idle...

Before I went fully SSD/m.2 the loudest thing in my case was my spin drives. Well not sound as such, more reverberation/vibration.

Under a heavy load you do get some fan noise, but a heavy load in my case is gaming, and when I'm gaming I have my speakers on... And the speakers/in game sound track or what ever is loud enough to easily drown out any fan noise by several magnitudes, so for my scenario it's kind of a moot point.
 
My secondary pc has a cheap case as in £35 with cheap fans and that does reverberate a bit.
I made a mat for it to sit on out of some rubber sheeting with a slice of polystyrene in between as a vibration isolator and that worked quite well.

But don't underestimate a good quality pc case combined with good quality fans.
Cheap PC cases often come with super cheap fans, so your kinda starting on the back foot straight away in that scenario.
 
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If you are set on the fanless route, a Streamcom FC8 or similar case would be a decent option. It uses the aluminium case as a giant heatsink.
The Pico-psu is also fanless, only downside is you will need an external power brick.

Used one myself with a i5-6500 (65W) for Plex and Citrix. Never did anything intensive to tests the limits however.
For me it was more about looks in the living room as opposed to silence.

As above posts, a large cooler with decent fans at low RPM is pretty much inaudible.
 
How about a passively cooled case that has attachments for both the cpu and gpu? Streacom is developing something that was showcased back at CES2024 and i think is due for release soon. Worth checking out but its really expensive as you can imagine.

Edit: Its called the SG10
 
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Deadly Ferret said:
I've been happy with my computers for years, doing nothing more than adding storage over the last seven or eight years, so my knowledge has fallen way behind. (No games, no CAD, no demanding usage of any kind.)

I was just searching on the internet to see what the current state of things is with passive cooling of CPUs. First time I looked in to this for nearly a decade. I found several articles written circa 2022/2023 which gave me the impression that it's a dodo now/nothing new developed for several years. One of those 'recent' articles was recommending a passive cooler I've had gathering dust in my shed since about 2016, a big copper thing called NoFan CR-80EH good for processors up to 80TDW.

Does anybody know differerently please/are there newer better options? I'd like to build a new but basic machine for non-demanding office use, and would prefer it to be silent. A quick look on the CPU section of OcUK tells me it's probably going to be an AM4 socket option. Remarkably my old copper thing apparently fits that socket (according to a 2022 article) which didn't exist when it was made. I suppose the architecture is very similar. I do like making use of existing items, but I can't help thinking 'modern processor = modern cooler'... Also, I was trying to remember why I wasn't using this cooler which was probably bought for a 65TDW processor I have air cooled. I think either the installation process made me worry about damaging the CPU and I wimped out, or in the end I went through with it but was concerned about the temperature I was getting with it.
Click to expand...

I have built a few PC's like that, and what I use is the T processors. They are perfectly fine and for non intensive stuff you don't even need a graphics card. They can readily be cooled passively (although I used active cooling the fan idles at all times!). I would probably just buy the largest heat-pipe cooler I could find and set the fan curve to off until it hits an unreasonable temperature.
 
As far as I know, the best passive CPU cooler currently available is the Noctua NH-P1. I don't have personal experience with it, but from what I've seen it should handle a CPU with a nominal 65W TDP alright. The downside is that it's huge and expensive.

I have a CR-80EH that works nicely to keep a 35W TDP CPU (AMD 3400GE) cool enough. A 65W CPU would probably be pushing it to the limit in a truly fanless system.
 
I wanted to say thanks to everybody who has contributed. I'm intending to do more research over the weekend when I next have time to kill, following up on all the information kindly provided here. :)
 
If it's a low power chip like a 5600G/8600G then a big 140mm dual tower would probably work fine without any fans. I'd try the Thermalright FS140 (£26.39), and if it thermal throttles you could just put 1 fan on at really low speed at about 400rpm.
 
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