Question Normal temps for overclocked R9 3900x?

epikness

Commendable
Oct 17, 2017
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I've managed to overclock my new liquid cooled 3900x to 4.4ghz across all cores at 1.3v. My temps at idle are in the mid 30s, and at full load go into the mid 70s, and sometimes into the low 80s. Just wondering if these temps are normal since I just built this beast.
 

zx128k

Upstanding
Nov 23, 2019
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4.4GHz all cores from a 3900x at 1.3volts is unbelievable. Also cooling is going to be an issue, once you run a HEVC load. Typical overclock's in the table below.

3900XNot Tested4.00GHz1.200V100%
3900XNot Tested4.05GHz1.212VTop 87%
3900XNot Tested4.10GHz1.225VTop 68%
3900XNot Tested4.15GHz1.237VTop 35%
3900XNot Tested4.20GHz1.250VTop 6%
source
 

zx128k

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Nov 23, 2019
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Idk mate I’ve got mine at 4.4 with a 360 rad @ 1.33v and I run idle at about 42c. 78c under 100% extended load.
What load, because I have the best 360 rad (all copper block) and my temp's are higher in prime95 8kfft with a 3800x @ 4.4GHz. Also most 3900x won't do higher than 4.2GHz all core overclocks and remain stable.

What stability tests have you run? Have you tried a HEVC load?

AyoKeito

AMD 3900X / ASUS x570 Pro1 point · 2 months ago · edited 2 months ago

For CPU-Z stress test, i'm sitting at 80-85C.
During Adobe Media Encoder 4K x264-x265 very slow with Voukoder plugin (ffmpeg essentially) it's 85-93C. But i have to say that i use manual 4100-4000 1.3V profile for those encoding jobs. PBO would most likely be hotter. FHD encoding jobs, are, on the other hand, sitting at ~70C.
I'm using water temperature to adjust fans RPM and avoid fans spinning up on desktop and light workloads (see this thread). As for temperatures, those are pretty much what i had on Deepcool 360 AIO.
EK 360 slim radiator with 3 pull Vardar fans, EK Velocity water block.

source

360 AIO stock 81.5c full load. 4070MHz all cores. https://www.amazon.com/Enermax-LIQTECH-Liquid-Cooler-ELC-LTTO360-TBP-W/dp/B07N8XDKQ9?tag=hardfocom-20
the temp difference betweet the aio and the custom loop is about 1-3C in most tests.
I have a 3900x cooled with an Enermax LiqTech II 360 and when running the AIDA64 stress test for an hour I was right around 83c and all cores at 4ghz.
Mine at wide open is hitting 90c in some benches even with an XSPC waterblock and custom loop. https://hardforum.com/threads/3900x-is-a-toaster-oven-mine-solved.1983849/


 
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zx128k

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Do you know the FIT value for your 3900x? The FIT value is around 1.325volts, if your vcore voltage is above your FIT then your cpu will likely degrade. This will likely happen because your vcore could be too high (above FIT), temperature is high and the manual frequency is above Fmax. With your setting there are reddit reports of degrading within two months.

You need to set your CPU to stock, then work out your FIT. If you want to be able to find this voltage turn on PBO and max PPT, TDC and EDC and run a worse-case workload. Prime95 8k fft or aida64 cpu fpu will work. Then look at your vcore, it should be around your FIT value.
 

epikness

Commendable
Oct 17, 2017
13
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1,510
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Do you know the FIT value for your 3900x? The FIT value is around 1.325volts, if your vcore voltage is above your FIT then your cpu will likely degrade. This will likely happen because your vcore could be too high (above FIT), temperature is high and the manual frequency is above Fmax. With your setting there are reddit reports of degrading within two months.

You need to set your CPU to stock, then work out your FIT. If you want to be able to find this voltage turn on PBO and max PPT, TDC and EDC and run a worse-case workload. Prime95 8k fft or aida64 cpu fpu will work. Then look at your vcore, it should be around your FIT value.
I don't think I need to worry about that because mine is at exactly 1.3v. I guess I got pretty lucky with the silicon lottery, being able to overclock to 4.4ghz at only 1.3v across all cores. Thing is I haven't manually overclocked the best cores higher either, so it could probably go even further.
 

zx128k

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I don't think I need to worry about that because mine is at exactly 1.3v. I guess I got pretty lucky with the silicon lottery, being able to overclock to 4.4ghz at only 1.3v across all cores. Thing is I haven't manually overclocked the best cores higher either, so it could probably go even further.
If you are above your FIT voltage, you will be above your Fmax with all cores 4.4GHz and with temps 80-95c. You will likely degrade. If your chip is as good as it seems and passes aida64 cpu fpu @ all cores 4.4GHz then its worth making sure you are below your FIT. FIT is around 1.325 volts so you could be alright at 1.3 volts but some chips are lower and others higher. FIT is unique to each chip.

"For x% over fmax, voltage must be lowered by x% of the maximum FIT voltage, in theory anyways, that may not be safe in actuality. Though I would doubt it not being safe." - MadLad81#9445 (discord tag)
View: https://www.reddit.com/r/overclocking/comments/ejd5c9/1325v_is_not_safe_for_zen_2/fcxrk78/

If you push over Fmax you are going over the rated spec meaning your current draw will be higher then spec. Let's just say at 4.2ghz 1.3V you are pulling 100A. In this situation you are on the FIT maximum voltage and on the Fmax so you are within spec.
If you then raise the clocks to 4.242ghz at the same 1.3V your current will be ~101A. Due to close to linear current increase when frequency is raised. (4.242/4.2 * 100 = 101)
Now if you lower your voltage by the same amount you raised your frequency (1%) your current will be back in safe limits. This works because voltage raises or lowers current by the same amount that is was changed. (101 / (1.3/1.287) = 99.99)
This formula isn't perfect but works pretty well.
 
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