Question Plan - CPU compatible with RAM?

[thill3]

I'm planning on a Ryzen 9 7900 CPU for ane build for Convolutional Metal Networks and other ML/AI.

Newegg says that the processor works with DDR5 5200 and can only handle up to 128GB of RAM.

If I start with Corsair Vengeance 2x48 DDR5-5600 then the CPU is going to limit it to 5200 as soon as things boot?

And if I want to upgrade my RAM in the future then will I be able to use another set of 2x48 DDR-5600? Or will I be effectively limited to an additional 2x16 (or just replacing with 4x32)?

 

[hotaru.hino]

RAM by default boots up in a lower, mostly compatible speed, which is typically DDR5-4800. You have to set the speed via its XMP/Expo profile or manually doing it yourself.

As far as adding more RAM goes, you can get more RAM, but the system won't be able to use more than 128GB. So it's basically a waste to get anything more than an addition 32GB.

 

[CountMike]

I'm planning on a Ryzen 9 7900 CPU for ane build for Convolutional Metal Networks and other ML/AI.

Newegg says that the processor works with DDR5 5200 and can only handle up to 128GB of RAM.

If I start with Corsair Vengeance 2x48 DDR5-5600 then the CPU is going to limit it to 5200 as soon as things boot?

And if I want to upgrade my RAM in the future then will I be able to use another set of 2x48 DDR-5600? Or will I be effectively limited to an additional 2x16 (or just replacing with 4x32)?

5200MHz is just IMC starting frequency over which it's considered overclock, otherwise it could work with much higher frequency. 128GB is Limit on all consumer desktop CPUs as well as windows, only server grade can go over.
Another problem is using 4 sticks which can overload IMC so you may have to use sub-6000MHz RAM. Adding more memory that didn't come in same kit is not sure to work at all or may cause instability problems.
Memory frequency can be adjusted automatically using XMP and in case of AMD also EXPO if RAM has it and BIOS supports it. All have options to adjust it manually.

 

[Colif]

its not really the cpu you need to think about, its if the motherboard works with the ram. No point choosing ram that hasn't been tested to work with the board, or you might run into problems.