The Right DDR5 RAM Speed for my CPU/Mobo?

[Pwnjones]

Hello, I have purchased an intel i7 13700k with an MSI MAG Z790 DDR5 mobo. The MSI website lists a compatible Corsair RAM SKU for this CPU/mobo combination as: CORSAIR CMK32GX5M2B5200C38 ver3.43.01, which is the VENGEANCE® 32GB (2x16GB) DDR5 DRAM 5200MHz C38 Memory Kit. That kit seems to have been superseded by the SKU: CMK32GX5M2B5200C40 (VENGEANCE® 32GB (2x16GB) DDR5 DRAM 5200MHz C40). Is this correct? Am I OK to purchase this newer SKU for my system? I want to be sure I buy the highest stable speed RAM for my system.

Thank you,

Jonathan Jones

[c-attack]

The C40 version is dual rank vs the single rank on the C38 kit.  I am not sure I would say one replaced the other and they both appear to be Micron A die.  So the dual rank may have slightly better copy scores and the C38 single rank might have slightly better latency and read scores, but you'll never see that difference outside of benchmarking.  If that is the kit you want, you should based on price and availability.

 

However, if you really are after the highest stable frequency you will be leaving a lot on the table at 5200.  Top end certified kits will be up near 7000 MHz, but anything in the 6000-6400 range is a lock for plug and play and should not require active cooling.  

Edited March 27, 2023 by c-attack

[Pwnjones]

OK thank you! I was confused because PC part picker warned me that the highest stable RAM speed for my CPU was 6600, but after watching a Jay's Two Cents video he mentioned I should be checking for motherboard speed compatibility, or QVL, and the MSI website only mentions 4800 natural and up to 5200 via something called XMP.

[c-attack]

MSI sets up their compatibility page a bit differently and there are tabs for each possible CPU type.  I don't know how part picker grabs the info, whether automated or someone has to manually enter it.  6000 would be the max if you had a Kaby Lake 12 series CPU.

https://www.msi.com/Motherboard/MAG-Z790-TOMAHAWK-WIFI/support#mem

 

I don't think that link retained my search specifications.  Above the graph select "13th generation CPU K-series" (far right) and search Corsair in the box.  You can then sort by supported speed (highest to lowest).  You probably can run everything on the list, but any kit that runs 1.45v XMP may need active fan cooling in Summer and there is a small chance you need to tweak some settings at 6800-7200.  Between all those Hynix M die models in 6000-6600, those will similar timings and lower voltage (1.30) will run cooler and likely have more overclock room above the XMP speed should you become interested.  After that it's going to be price and availability.  Things have smoothed out pretty well now with small, gradual price increases for small, gradual increases in frequency/performance.  The top end kits still carry a big premium.  

 

XMP is a preset for overclocking.  This is the on the box speed and activated in the BIOS.  On the MSI website "supported speed" = XMP preset speed.  

Edited March 27, 2023 by c-attack