This is not new, and there have been posts about it in the past - but I am posting here & now as I got caught out by this.
Most will be on top of this, but maybe there are one or two others who, like me, have not been that close to CPU/memory tuning when it comes to getting the most out of the Sim.
Long and short - I have a ASUS ROG Strix Z590-F Gaming motherboard, a 11900k CPU, RTX 4090, and DDR4 3200 RAM - but the motherboard BIOS was set to Auto when it came to the RAM speed - so it was at 2133 and not 3200.
Changing this to to the profile XMP I gave me a signiticant bump in performance.
Recently, I have been guaging relative performance of the CPU using the OXRTK rdr CPU counter. Tipping point has been at around 15ms, when the GPU is not stressed.
For my test flight route, rdr CPU ranged from 12ms to 20ms.
Chaning to XMP I changed that to 10ms to 14ms - a 20-30% improvment on that measure, and everything below the tipping point.
Now I get a much smoother flight, even low over the built up areas.
It hasnt fixed everything - I still get the odd ‘jump’ - but it has been the biggest ‘tweak’ I have ever had.
One warning if you wish to do the same - check what your motherboard supports and how to tweak it. Getting it wrong can result in your PC no longer booting to BIOS - though this should be fixable by resetting the BIOS CMOS.
I can add that not all memory will run on advertised XMP or EXPO profiles. You may need to raise the voltage, or in my case, counter-intuitively lower main voltages and raise secondary voltages. You can also tighten primary and/or secondary timings on most RAM modules. Any changes require heavy testing. The most prone for errors in the fastest time for me was a free and old TestMem5. If it can get a single pass without errors, let it run for a full cycle and that would be a good indication of RAM stability. My DDR5 6000 CL32 RAM refused to boot at advertized XMP profile (AM5 7950X3D CPU). But I managed to make it run at 6000 CL30 without loosening any timings. But I could not tighten the timings further either.
OP has an Intel Rocket Lake CPU. I have an AMD CPU, and I make sure to manually set the FCLK in the BIOS to 1/2 the RAM frequency, which sets the Infinity Fabric memory controller timing. Intel call it IMC.
For me, my RAM runs at 3600MHz using XMP2, so I set FLCK to 1800MHz. The FCLK defaults to a different number, which can decrease RAM performance.
For Intel MOBO’s and Rocket Lake CPU’s, you should be able to set the ‘CPU IMC’ to basically do the same thing.
“The BIOS screenshot shows two operational modes for the CPU IMC (integrated memory controller) and the DRAM clock on MSI’s Z490I Unify. Apparently, Gear 1 runs both in a 1:1 ratio, while Gear 2 puts them in a 1/2:1 ratio. It’s similar to how the FCLK works on Ryzen processors.”
Soon I’ll make a video about the difference in game results after upgrading ram memory from 16 to a high quality 32gb. Stay tuned for that for the ones who are in doubt upgrading is worth it.
Are there any differences between running, say, 32GB in two slots or 64GB in four slots - that is, if MSFS needs less than 32GB, is 64GB going to unnecessarily tax the memory controller? Or is the difference too small to be significant?
It’s different for everyone, if you’re running tasks while playing, for virtual airlines FSuipc for example, FSrealistic add on for cabin effects and recording video, just naming a few. Than 64 could make sense.
If you’re just playing the game and nothing else is running in the background you’re perfectly fine with 32, that’s more than enough.
Experiment. You can’t hurt anything by choosing one option, flying with dev mode Display FPS on, then repeating the test using another option. Do your best to minimize other variables. Turn Live Weather OFF, park the same plane at a ramp, note FPS and other metrics. Repeat while spawning at the same place on the World Map (over ocean, over terrain, over Tokyo.)
There can indeed be a difference. On some boards memory speed might even be throttled if you use all four slots, for the reason you stated.
In my personal experience I went from 2 x 16GB DDR4-3600/CAS14, to 4 x 16GB of the same RAM. No difference. CPU-Z reported the exact same metrics. And PassMark benchmark reports the same memory throughput. AMD B550 motherboard.
I increased my memory size because I find having a RAM drive very useful for certain things. I currently allocate 14GB to a RAM drive. If I only had 32GB, I’d only have 18GB left for everything else.
I’m pretty sure that 2 x 32GB sticks would be optimal, but I didn’t want to just throw my expensive 16GB sticks away.
