The CPU test score went down by about 15% because I changed my RAM settings.
The CPU test score went down by about 15% because I changed my RAM settings.
Hi, I checked the DRAM Calculator yesterday and changed my memory settings from 16-18-18-38 at 3600mhz to 15-17-18-18-38 at 3733mhz. This includes a 1.42 volt DDR voltage, a 1.1 volt SoC voltage, and Infinity Fabric 1-1 with the memory running at 1866mhz. Everything runs smoothly, and I did some hours of stress tests on memory without getting any errors. But when I ran a CPU benchmark using PassMark, my score went down from 33,350 to 29,000 both before and after changing the memory settings. I tried running it a couple more times with similar results, but then I reset my memory back to base timings and frequency, and the score jumped right back up to 33,350. Is there any chance that making the memory faster or better timing is hurting CPU performance? Note that I turned off Power Down Mode and Gear Down Mode while overclocking memory because the CPU stays at stock settings. My system: Ryzen 3900XT running on default settings, NZXT Kraken x63 (CPU temps stayed low in the 30s when idle and hit 60s under load, sometimes peaking to 70s for a few seconds), Crucial Ballistix Gaming memory with 2x8gb sticks at 3600mhz CL16-18-18-38 (Micron E die), Gigabyte Aorus Elite x570 motherboard on the latest F20 BIOS, and Sabrent Rocket PCIe 4 NVMe SSD.
The maximum speed limit for the processor is a set number. If you hit around 3733 MHz, it breaks that limit. The system automatically changes how things work right away. As soon as the speed drops slightly below that mark, it switches back to the normal way again. This means the RAM keeps switching between different modes all the time. Because of this switching, your overall power boost is lost for a faster connection frequency. That's why the best setting for third-generation Ryzen chips is usually 3600 MHz, even though real-world speeds go higher like 3733. Motherboards aren't perfect anyway; you can only get around that by manually changing settings in MCLK, FCLK, or UCLK, which is very advanced and usually only done when the RAM is at least 3800 MHz or better.
The infinity cloth timer falls to a 2:1 ratio when time hits around 3600. At 3733, your real-world speed comes out to roughly 1866.
Thanks for getting back. The Ryzen 3900 (and a few other ones too) have an infinite clock, which goes from 1 up to 3733 MHz. That's why I picked this number as the target to bump my memory frequency to.
I stepped back just a bit to set the timings at 16-18-18-38 on my memory speed to 3733mhz. Then I tightened those settings up. Now all my benchmarks are higher than before, and nothing comes up in memtest after running for a few hours. Everything is working well!
I think you are wrong, if your memory clock is higher than 3600, the ratio will be 2:1 unless you manually change something in the BIOS. If it's not the Intel FPU that causes the drop, then it must be the UMC, but I am pretty sure one of those drops above 1800.
Sorry, as shown on the first post, my memory speed matches the clock exactly. That perfect ratio works up until the DRAM hits around 3733 mhz (if you check online, people have actually tested it to 3800 mhz). I am 100% sure of this fact - my infinity clock is set at 1867 mhz and that's exactly what I see in action.
Yeah, that's true. The speed limit for the signal between your processor and RAM is around 3733 megahertz. It only makes sense to have 3600MHz memory because higher speeds usually mean worse performance after a certain point. So using standard slower memory is actually the better choice here.
3200 MHz is the best guaranteed speed, while 3600 MHz is the top limit. There are some online videos showing how jumping higher forces the chip to slow down or change ratios. I've seen these in several places before. But if you want real benefits, you really need to clock it at 4000 MHz or above. That extra boost isn't worth paying a steep price for just a tiny bit more speed.
The maximum speed for Intel frequencies isn't endless. If your RAM clock hits 3733.01MHz, the system stops that high number instantly. Then it flips to a different timing mode right away. As soon as the clock drops below 3732.99MHz, it goes back to the old simple setting. So this RAM is trying very hard to switch between modes constantly while you try to make your CPU faster. That constant switching kills some of that speed boost because the computer spends too much time changing things instead of doing one big thing well at a time. This is why the best performance point for 3rd generation Ryzen CPUs is 3600MHz, not the real 3733MHz number. Motherboards can't make perfect settings, and that's okay because you can just take charge yourself by adjusting MCLK, FCLK, UCLK clocks manually if needed. But this kind of trickery needs really advanced knowledge, and most people only do it on RAM speeds that are at least 3800MHz or higher.