08-03-2023 01:58 AM
On a X670E-Pro, I can get the stock speed 5600MHz (manually set) from a single Corsair Vengeance DDR5 64GB(2x32) kit (CMK64GX5M2B5600C40). CPU is Ryzen 9 7900.
However, I can't get this speed from two kits (4 modules, 128GB). Instead I get BIOS safe mode.
Note, the second kit is actually CMK64GX5M2B5600Z40 (Z instead of C, don't think there's any real difference).
I haven't done any overclocking (manually setting RAM to it's official speed doesn't count, right?).
Should my setup handle this? Do I need to overclock or something?
I asked official ASUS support and they said "Based on the QVL list for the PRIME X670E-PRO WIFI-CSM motherboard, both of the memory kits are not listed." so they won't help.
Other specs:
GPU: GeForce 3080.
PSU: SilverStone ST75F-GS 750W.
08-03-2023 03:27 AM
1. Combining and mixing memory kits isn't supported by memory or motherboard vendors. This is because memory vendors bin and validate the memory kit in the density in which it is sold. If you combine memory kits the settings in which the kit is validated are no longer valid. You would need to return one or both of the memory kits and purchase a single kit validated for the density and frequency you are trying to run.
2. Setting EXPO or setting the memory frequency, timings and voltage manually are no different. AM5 CPUs natively support up to 5200MT, anything beyond this is overclocking.
3. It's always best to stick to memory kits present on the QVL as these will have been validated by ASUS. You will see on the QVL that the number of DIMMs supported is also listed per kit.
08-03-2023 03:45 AM
There are 4 DIMM kits on the QVL.
Depends on what you consider a downgrade. Populating more DIMMs for high density has always inherently come with sacrifices to overclocking.
The platform supports four DIMMs just fine when stock. The limitations come down to what the CPU can do beyond specification when all slots are populated.
08-03-2023 04:41 AM
Is it this QVL list: https://www.asus.com/motherboards-components/motherboards/prime/prime-x670e-pro-wifi/helpdesk_qvl_me... I don't see any 4 module kits there.
When you say AM5 supports 5200MT, that equates to 2600MHz right (2 transfers per clock for DDR). Seems awfully slow, as all DDR5 sold here (pricespy.co.nz) is 4800MHz. I guess I'm misunderstanding ram speed somehow.
Is 4x3600MHz actually faster than 2x5600MHz in terms of raw bandwidth or end-user performance?
08-03-2023 05:30 AM - edited 08-03-2023 05:30 AM
Filter by 4x16GB, I see a few there.
You have misunderstood as far as to say 5200MT is the transfer rate, as is 4800MT for PC5-4800 specification (see JEDEC website for more info). Kits are still referenced in MHz for sake of simplicity.
Seems a bit late in the day to get caught up in the semantics of that when you've purchased two kits already 😄.
If you want faster speeds, best to go for a board more geared towards overclocking such as the Strix or Hero, but generally speaking the best performance is found when using 2 matched DIMMs from a single kit.
08-04-2023 08:09 AM
Ugh, that QVL page confused me. It shows "< 1 2 3 4 >" even on page 4, which on most sites indicates there's only 4 pages. I might mention it to them.
"simplicity" seems a kind word for it. I again got confused and, after a brief google, it seems somewhat controversial.
Maybe I need to go buy a second CPU and mobo to go with my spare ram now. 🙂