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Processors

hekynu
Journeyman III

Ryzen 3900X only at 3999Mhz under full load

Hello, i have no experience with Ryzen CPUs so i wanted to ask.

So, as the title says my CPU only reaches 3999Mhz on all cores under full load in Cinebench R20, shouldnt it boost to around 4.2 Ghz? Temps are 68-72C, never reached 75C. Is this normal or is the CPU preventing higher temperatures?

PC Specifications:

CPU: Ryzen 9 3900X

CPU Cooler: Fractal Design Celsius+ S36 Prisma

Motherboard: MSI MEG X570 ACE

RAM: Adata XPG Spectrix D41 16GB (2x8)

All drivers are on the newest versions. BIOS is on the latest non-beta version. Chipset driver is also on the latest version

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10 Replies
nero9937
Journeyman III

Re: Ryzen 3900X only at 3999Mhz under full load

https://www.pcgamesn.com/amd/ryzen-9-3900x-overclock#:~:text=The%20Ryzen%209%203900X%20is,CPU%20life... 

According to this article, only 6% of chips can reach 4.2 GHz on all cores, and that's with a manual, forced overclock. I'd say that's intended behavior, if you don't use overclocking features.

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hekynu
Journeyman III

Re: Ryzen 3900X only at 3999Mhz under full load

Thats probably true... I saw Cinebench R20 scores that are that are lower than they should be, around 6800, and then there are scores like 7200 or even 7300 on stock settings. These ones that reach 7200 are probably the 6%. Mine R9 3900X gets around 7100, so i guess thats normal.

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mstfbsrn980
Grandmaster

Re: Ryzen 3900X only at 3999Mhz under full load

CPU core voltages applied by each motherboard is probably very close to each other but not the same. You can try to increase its performance a little more by trying to undervolting your processor with the BIOS.

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hekynu
Journeyman III

Re: Ryzen 3900X only at 3999Mhz under full load

Already tried that with a 1.35V override and a 1.4V override. Both times the cpu dropped to 0.9V and only got to 3Ghz under full load. So i dont know, maybe i did something wrong.

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mstfbsrn980
Grandmaster

Re: Ryzen 3900X only at 3999Mhz under full load

What is the speed for CPUZ stress test?

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hekynu
Journeyman III

Re: Ryzen 3900X only at 3999Mhz under full load

CPU-Z shows 7885 when stress testing

Temps are around 70C

CPU is at 3999Mhz

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mstfbsrn980
Grandmaster

Re: Ryzen 3900X only at 3999Mhz under full load

CPUZ should have shown higher. You can go into the BIOS and try manually giving 105 watts of TDP limit. I can't think of any other suggestions...

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hekynu
Journeyman III

Re: Ryzen 3900X only at 3999Mhz under full load

I couldnt find any TDP settings or anything like that, so instead of an OVERRIDE that i did last time i set an OFFSET of 0,1V and then i got around 4050 Mhz in full load. I guess i will test it when a stable release of the zen 3 bios releases

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mstfbsrn980
Grandmaster

Re: Ryzen 3900X only at 3999Mhz under full load

Sorry. I could not help you. However, your system has a performance problem caused by the BIOS. But how to fix this, I don't know. I only wrote general things...

Your system BIOS may not properly implement TDP for your processor, or the multipliers by which the processor speed is determined may not be applied, or the voltage may be high and the processor may not be properly turbo itself when limitted to TDP.

Goodbye...

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