The CPU benchmark decreased by 15% following an optimization of memory settings.
The CPU benchmark decreased by 15% following an optimization of memory settings.
Hi, I tried DRAM Calculator yesterday and adjusted my memory settings from 16-18-18-18-38 at 3600mhz to 15-17-18-18-38 at 3733mhz (1.42 DDR voltage, 1.1 SoC voltage) using Infinity Fabric 1-1 with a memory frequency of 1866mhz. Everything worked fine, and I completed several hours of memory stress tests without any issues. However, when I ran a CPU benchmark with passmark, my score fell from 33,350 to 29,000 (before and after the memory overclock). Running it a few times gave similar results, so I reset my memory to base XMP timings and frequency, and the CPU benchmark returned to 33,350. Could you help figure out why the CPU performance dropped despite better memory timings and frequency? Also, I turned off Power Down Mode and Gear Down Mode during the overclock. The CPU is still at its stock configuration.
The IF limit remains finite. When the RAM reaches 3733.01MHz it exceeds the threshold, triggering an immediate switch to a 2:1 ratio. As it then drops to 3732.99MHz it reverts to a 1:1 ratio once more. This frequent switching causes the RAM to constantly toggle between ratios, reducing its overall performance enhancement for quicker IF speeds.
This explains why the ideal sweetspot for the third release Ryzens is at 3600, not the actual 3733MHz. Motherboards are never perfectly precise, and this issue arises naturally.
The best solution involves manually adjusting the IF speeds in parameters like MCLK, FCLK, UCLK, etc., which requires advanced knowledge and is typically applied only to RAMs at 3800MHz or higher.
the infinity fabric clock operates at a 2:1 ratio beyond 3600, resulting in an effective speed of approximately 1866 at 3733
Thank you for your response. The Ryzen 3900 series, along with some others, features an infinity clock that operates between 1 and 1,5333 MHz, which is the reason I selected that frequency for adjusting my memory speed.
I think you're mistaken, any memory clock over 3600 leads to a 2:1 ratio unless you adjust it yourself in the BIOS. If it's not the condition that causes it, then it's the UMC; I'm pretty sure one of them drops above 1800.
Sorry, according to what I originally wrote, my infinity fabric matches the memory clock exactly. The 1-1 ratio works until at least DRAM speeds of 3733, though some people have achieved 3800mhz with it. I’m certain I’m correct—I set it to 1867mhz and it confirms that.
That's correct, 3733MHz is near the limit for IF at !:!:! It turns out 3600MHz RAM typically offers the best balance of latency and frequency after that point, making it the most efficient choice.
3200 is the preferred guaranteed clock
3600 is the maximum 1:1 clock
There have been demos where jumping any higher forces the fabric to go into a ratio. The videos are online. I have seen multiple examples. But to get any benefit you have to go really fast 4000MHz+. That is a very expensive bump for minimal improvement.
The IF limit remains finite. When the RAM reaches 3733.01MHz it exceeds the threshold, triggering an immediate switch to a 2:1 ratio. As it then drops to 3732.99MHz it reverts to a 1:1 ratio once more. This frequent switching causes the RAM to spend considerable time toggling between ratios, reducing its overall performance enhancement for higher IF speeds.
This explains why the ideal sweetspot for the third release Ryzens is at 3600, not the actual 3733MHz—motherboards are never precise or perfect.
The only solution is to manually adjust the IF speeds in parameters like MCLK, FCLK, UCLK, etc., a complex task typically reserved for advanced users and usually applied only on RAM clocks of 3800MHz or higher.