Sanity check on 3900x heat issues...

Ok, I am building two 3900x rigs to replace two i7-6700k rigs that I used with Cooler Master V8 GTS High Performance CPU Coolers (Vapor Chambers) for several years.. Went AMD for the first time in 15 years....

I am used to temps (and space heaters as it were) that are pretty low/cool...

So I start with the 3900x's. First chip I think is just a poor Si bin draw. With a Noctua D-15 I am idling at 40+ C. Mild desk top usage kicks it up immediately...gaming 60+ C. Pop in the second CPU. It is a few degrees worse....UGH...

So I am not overclocking. Read about the voltage issues (Asus crosshair VIII hero thinks 1.45 is a good starting voltage...ugh). So I am running DOCP (XMP) on my 3600 mem, but am running stock everything else. I am undervolted at 1.2 on core. That seems stable. That helped the heat temps a few degrees.

So I order an AIO. Installed the ARCTIC Liquid Freezer II 280 today. What a pleasure compared to messing with the H100i's I bothered with a few years back. I am now running idle at 28-32 C....gaming 45-50...

Considering that the ARCTIC Liquid Freezer II 280 is cheaper than the DH-15, and actually has fewer wires...and mounts easily in my Corsair 540 air carbide case (top mount), this seems the only way to go...

Have folks undervolted more on the 3900x? Am I missing something obvious? I want to push this technological terror, but with temps this high out of the gate...seemed like I needed to change things up first.

Mine seems to be crap silicon, but my temps stay in the upper 60s, low 70s in Prime, like the chip won't allow itself to run any hotter.

This is Prime95 with an H100i cooler


It was sitting at 58*C an hour later when I shut down Prime95. I am guessing the garage got a little cooler, I wasn't really paying attention to ambient temps.

OK, so both of you guys are also running AIOs.....I take it you are running all the Prime 95 tests...or are you cherry picking out the FFT, AVIX, etc.? Thx for the replies.

knox1711 said:

OK, so both of you guys are also running AIOs.....I take it you are running all the Prime 95 tests...or are you cherry picking out the FFT, AVIX, etc.? Thx for the replies.

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I just ran Prime95 as is. fired it up and hit start.

with the stock cooler it was sitting around 85*

I did mess with the auto overclock setting in the BIOS and it set it to 4Ghz @ 1.05 volts and was stable and cool with the stock cooler, 75* in Prime95, but it didn't boost or anything, just sat at 4Ghz.

Zepher said:

I just ran Prime95 as is. fired it up and hit start.

with the stock cooler it was sitting around 85*

I did mess with the auto overclock setting in the BIOS and it set it to 4Ghz @ 1.05 volts and was stable and cool with the stock cooler, 75* in Prime95, but it didn't boost or anything, just sat at 4Ghz.

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Stock cooler? The wraith prism? OMG, I have crap silicon then.....with a Noctua d-15 I hit 95+ C after 5 min of Prime 95 (when the FFT test kicked in....)

knox1711 said:

Stock cooler? The wraith prism? OMG, I have crap silicon then.....with a Noctua d-15 I hit 95+ C after 5 min of Prime 95 (when the FFT test kicked in....)

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Ya, the Wraith cooler.



I had the H100i outside the case during testing since the case I had couldn't fit it inside.




this is the setup installed in my friends case when he brought it over for me to finally swap the i7 4770 to the 3900X for him,

I have had mine for a little over 3 months. I have tried several coolers and they all have it sitting around high 30's idle and in the 40's when just doing desktop stuff. Running Prime95 Blend with AVX2 on it will run up to 95 eventually then settle back down into the high 70's. But starts out in the high 50's to low 70 range. Like right now typing this it has gone up to 74 while I was thinking and typing, running Prime95 in the background. It has not broke 75 yet. Anyway they do run warm that is for sure. This EVGA cooler I am running now seems to be the best so far, but it could also be the new case as well. Either way I ran a Corsair H100i Pro, Corsaid H60, Noctua D15 and the wraith Prism before, the EVGA 280 has been doing great though. I run it in the front of the ThermalTake h200 case sucking in and 3 Corsair LL120's exhausting, 2 on top and one in back. While I flipped around and typed this the temp is now at 84 degrees still running Prime, clocks now at 3.95Ghz all core after 10 minutes or so.

This is after 40 minutes of Prime95. That is the highest the temp got so far according to HWINFO64. It stepped down to 87.8 degrees shortly after that screenshot and down to 3.95Ghz.

To answer OP, I just take the defaults in Prime 95, but mine also stays sub 4 GHZ when running Prime.

"my 3900x running pure stock and 100% 24/7 struggles to stay below 70 C and that is with a 480 mm radiator" @ https://www.techpowerup.com/forums/threads/ryzen-3950x-build-help.258856/post-4158752

erek said:

"my 3900x running pure stock and 100% 24/7 struggles to stay below 70 C and that is with a 480 mm radiator" @ https://www.techpowerup.com/forums/threads/ryzen-3950x-build-help.258856/post-4158752

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Try installing a fan or two.

60s not hot 70s not hot even 80s not hot under a full load.

Your stressing over nothing.

Make sure you are running the latest bios and AGESA microcode.

Under volt of 7nm is proven to be a performance anchor.

Your chips should be running at 1.32ish v full load. P95 small fft with AVX will.make any method of cooling except LiqN2 run at 90c plus which is considered hot.

SI lottery has nothing to do with it.

I ran a custom loop with 7x120mm and my 3900x idled at 32c avg room temp, games in the 40s and 50s and video compressed at 70 to 75c.

Even with all my waterblock and 7 radiator slots p95 avx made my chip hit 95c.

Welcome to packing such a dense core count into a tiny little chip.

tangoseal said:

60s not hot 70s not hot even 80s not hot under a full load.

Your stressing over nothing.

Make sure you are running the latest bios and AGESA microcode.

Under volt of 7nm is proven to be a performance anchor.

Your chips should be running at 1.32ish v full load. P95 small fft with AVX will.make any method of cooling except LiqN2 run at 90c plus which is considered hot.

SI lottery has nothing to do with it.

I ran a custom loop with 7x120mm and my 3900x idled at 32c avg room temp, games in the 40s and 50s and video compressed at 70 to 75c.

Even with all my waterblock and 7 radiator slots p95 avx made my chip hit 95c.

Welcome to packing such a dense core count into a tiny little chip.

Click to expand...

Thank you very much for the post. I figure sometimes something new comes along and you just have to change your thinking about how things should work...this seems to be one of those times. Thanks everyone for the info. I'll stick with the Arctic Freeze 280s and not worry anymore about the higher temps...

Also I recommend using HWInfo64 as its far far more accurate than Coretemp or any of those others.

Monitor the CCD1 and CCD2 temps and not the package temp. CCD temps are going to the actual die temps and you will see that they heat and cool much much faster than the overall CPU package does.