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The original was posted on /r/overclocking by /u/Brief_Platform_8049 on 2023-08-08 10:32:58+00:00.
I have a Ryzen 9 5950x on a ROG Strix B550-F Gaming (Wi-Fi) motherboard. So I decided to enable PBO and was using PBO2 Tuner to find the best values for my PC.
Basically what I did was set the PBO values to Auto in the BIOS, and then use PBO2 Tuner to modify the values. Then I run Cinebench R23 and note down the score for each combination.
After hours of tuning and testing, I decided that the following combination gave the best performance: PPT 205, TDC 135 & EDC 145. With those values I could get about 27500 multi-core score in Cinebench R23.
To make this setting applied at start-up, I put those values into BIOS. Saved and restarted the PC. Opening PBO2 Tuner and Ryzen Master showed that the values were correctly applied. The problem is when I ran Cinebench R23, I got a significantly lower score of about 26100 multi-core. I tried restarting the PC a few times and rerunning Cinebench, but the results were consistent.
So I am rather perplexed by this. Why is the CPU underperforming when PBO is set in BIOS versus being set via PBO2 Tuner? To analyse the matter further, I captured screenshots of HWiNFO64 while Cinebench was running the multi-core test. I did it for both cases, with PBO values set using PBO2 Tuner, and the values set in BIOS. The screenshots are as follows:
I highlighted the relevant values. You can see that in the first case (left screenshot), we got a max TDC of 135 A, max EDC of 145 A and max PPT of 189 W. The CPU Core Current reached a max of 135 A. On the second case (right screenshot), we only got a max TDC of 123 A and max PPT of 168 W. Only EDC reached the set limit of 145 A. CPU Core Current reached max of 123 A.
I don’t understand what is going on here. Why is the CPU performance seem to be depressed when PBO values are set in the BIOS? Can someone please help explain?