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Higher CPU temps

Cereal Bus

n00b
Joined
Jan 10, 2021
Messages
7
Just finished building a gaming rig for my nephew. Here's the build:

Lian Li PC-O5sx
Asus ROG Strix x570-i (mITX)
Ryzen 3700x
Corsair sf750 PSU
2x8G Corsair Vengeance
1G WD M2 nvme drive
Sapphire radeon 5700x Nitro
Noctua L9x65 cpu cooler

Case is cooled by two 120 mm exhaust fans on top, and both front and back are effectively open mesh.

Idle CPU Temps are high 40s. Under Prime95 testing, however the CPU occasionally spikes to 80s, and even hit 90. I can see it throttling. I'm not sure if his gaming will stress the CPU in any way similar, and I recognize this is a smaller case so temps may be a bit High, but it feels like something else is wrong besides just air flow. I expected the noctua cooler to perform slightly less than the stock cooler but this is a pretty dramatic difference.

The rest of the case temperatures and even hhe cpu package temp are actually surprisingly low, even during the torture test. So the issue is quite localized.

Some questions as I trouble shoot:

1) The voltage is steadily higher than a very similar rig I just built for my niece. Hers is typically in the 1.35v range compared to his 1.45v, and spiking to 1.5. Is it possible this motherboard is overvolting the chip I'm causing some of this heat?

2) There really isn't any more room in the case for case fans. I can attach a 120 mm fan to the back of the case and it will blow on the back of the motherboard behind the CPU. But I can't imagine that's going to provide any meaningful air flow or help cool this chip. How much CPU cooling is realistic to expect from a fan blowing on the back of the motherboard?

3) I pulled off the noctua to make sure I had appropriate coverage with the thermal paste. It was fully spread, so that wasn't it. Surprisingly the noctua paste did deliver a couple of extra degrees compared to the thermal grizzly.

4) is there a higher horsepower 92mn fan I should.be mating up to this heatsink? It's really thin(12mm I think) I wonder if a beefier fan is the answer.

I'd really like to avoid having to run a water block on this rig. It's a pretty compact build and I'm not really even sure where I could fit the pump.

Thanks!
 
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You stated the issue in the first line.
Only 2x 120mm case fans is terrible.

If you cant fit larger + more fans and a way to make air flow through the case, you need a new case.
 
look for a cpu voltage offset and set it to -.05v, that will helps a little but that heatsink isnt going to give you that good of temps, its barely better than the oem one.
 
You stated the issue in the first line.
Only 2x 120mm case fans is terrible.

If you cant fit larger + more fans and a way to make air flow through the case, you need a new case.
Thoughts on the side fan behind the mobo? It's behind the plate the mobo attaches to, so it won't really supply a ton of air, but it will blow on the back, right behind the CPU plate.
 
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look for a cpu voltage offset and set it to -.05v, that will helps a little but that heatsink isnt going to give you that good of temps, its barely better than the oem one.

I've only got 85mm of clearance. The noctua is about an inch from the glass side panel. Not sure theres a better cooler that fits inside of that dimension.

I'll take a look at the voltage offset. The voltage on this thing does seem high. Is 1.45v -1.5v normal?
 
I was also thinking about reversing flow on the top two fans, and having them blow down.

They're right above the cpu/vrm.
 
I've only got 85mm of clearance. The noctua is about an inch from the glass side panel. Not sure theres a better cooler that fits inside of that dimension.

I'll take a look at the voltage offset. The voltage on this thing does seem high. Is 1.45v -1.5v normal?
probably no better cooler, since the case is so small. temps are still within spec though...
yes, a lot of board give them a bit too much juice when on auto.

I was also thinking about reversing flow on the top two fans, and having them blow down.

They're right above the cpu/vrm.
its worth a try.
 
Prime95 is pretty extreme and does not represent any normal usage. Especially if you run the Small FFTs test. Even with beefy air coolers and AIOs people can easily hit 85 to 90 degrees on the new Ryzen processors.
 
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