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Discussion Starter #1
So I am thinking of building an SFF PC for a relative. They're a gamer and do a lot of productivity and VoIP stuff for work. I also want to make it darn near-silent at idle. Knowing my own 3800X, it really likes to get warm at default settings even when just doing random things like web-browsing. This leads to the fan speeding up before going down. Until I tweaked my settings to allow much higher operating temperatures, it sounded like my PC was breathing. I am also running an NH-D15. That's not an option in a mITX case. I am thinking of picking the NH-L9a-AM4 as the most likely contender for cooling, but this cooler is way way way smaller than the behemoth that is the big Noctua. I don't want it blasting all the time. As I understand it, the random heat spikes which lead to fan spikes are due to the self-boosting nature of Zen 2. This means that fan will go as high as it needs to until temperatures are met.

So what's the best way to keep a Zen 2 processor down in temps without losing too much power? I saw an absolutely wonderful drop in idle temps from my 3800X when I accidentally locked it at base clock (3.9GHz). Feels bad to lose the high end though: it would be nice to have access to those higher clocks under heavy load like gaming. I ended up reverting it to default behavior since obviously. As-is the spikes happen even when browsing the web as the CPU doesn't care what's loading it - just that it's going for maximal power for the current demand. So taking something like the 3700X, could I tell it to chill at something nice and low like 3.0GHz, and then spike to whatever overhead will allow under specific workloads? Further, suppose I was OK with losing the peak clock of 4.5GHz. Could I tell it have a boost range that is much lower than base - something like 3.0 or lower? I'd be super into the new 4800H mobile chip, but that's obviously not an AM4 part.

This thread is totally antithetical to the Overlock headline, but the forums have a lot knowledgeable folks. Maybe someone might have an answer. Could be I am just overthinking it too.
 

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Well the quick answer is a small AIO like the Corsair H80. Water helps with the small random heat spikes so it will run lower speeds plus exhausting heat out of the case. Which case are you using?
 

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The L9a can barely cool a 3400G and the noise can be noticeable after you set a decent fan curve. Tested this myself. The 3700X is much warmer and the L9a will probably be maxed out all the time and that is nowhere near silent.
 

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Discussion Starter #4 (Edited)
Well the quick answer is a small AIO like the Corsair H80. Water helps with the small random heat spikes so it will run lower speeds plus exhausting heat out of the case. Which case are you using?
Aha, OK. That's an interesting point. I've never used an AIO preferring big air, but I've also never built SFF. I don't have the case yet, but my choices right now are around the selection offered by Sliger and their SM series: SM550, SM560, SM570, or an SM580. They get progressively bigger. The SM570 is advertised as supporting 120mm AIOs and 120mm case fans, and the SM580 supports 240mm (I think) AIOs with 140mm case fans. The SM550 would of course be awesome to fit parts in, but it might be just a tad too small. Their support page does state that the SM550 could support a single 92mm AIO, but I have not looked into that one.

https://www.sliger.com/products/cases/sm550/

The L9a can barely cool a 3400G and the noise can be noticeable after you set a decent fan curve. Tested this myself. The 3700X is much warmer and the L9a will probably be maxed out all the time and that is nowhere near silent.
Oh, damn. OK. Thanks for the perspective. Sounds like an AIO might be a better bet. I looked up some reviews and the L9a seemed warm, which is where I thought underclocking the CPU some might help. Sounds like it might not be enough help without totally crippling the CPU.

Correct me if I am overthinking this. My biggest concern with AIOs has been longevity. I've never had a fan fail, and if one does fail, there's still a piece of metal attached to the CPU. Not tenable in the long-term, but at least some passive cooling that gives the user enough time to notice something being off. I don't know how long pumps last on AIOs, but if one dies you are left with basically nothing on the CPU. Then again, the L9a might be nothing as well without a fan, so I don't know.
 

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Discussion Starter #5
Found this neat vid. He's using an i7-4790K. Don't know if that runs hotter or not than a Ryzen, but it's interesting to see the air vs H60 comparison. The H60 sound was excellent - just a quiet woosh when heating up.

 

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Sadly I don't know of a fan speed "conditioner", maybe some of the aftermarket fan controllers allow you to set up ramp curves to smooth out the changes in speed. Or you would have to use Speedfan etc. software in background to control the fans, not sure it allows you to set up ramps but if it's open source it would be easy to alter the fan control to add these simple useful features.

If you want to go the bad way of reducing performance then set a short duration peak power limit low. That would be I think PL2 for older Intel CPUs along with duration of it.

Maybe some new motherboards finally offer fan speed ramp controls beyond Temp-PWM LUT.

Searching ramp control for fans, these can do it:

https://www.onsemi.com/pub/Collateral/ADT7473-D.PDF
https://www.onsemi.com/pub/Collateral/ADT7467-D.PDF
http://ww1.microchip.com/downloads/en/DeviceDoc/2303.pdf

No idea who uses them on mobos and offers those ramp controls.

With a good ramp you can filter out the spikes in temperate which on instantaneous fan control found on at least all older motherboards causes fans to go instantly from one speed to the other at no delay for no valid reason. Or you would need to smooth out the temperature reading over time, essentially making the ramp in the temp. read out.

This is what you want for a good fan control:
 

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