New RAM - Wont go past POST

[Victus]

Motherboard: ROG MAXIMUS Z790 HERO

CPU: Intel Core i9-13900KS

RAM: (x2) CORSAIR Vengeance RGB 32GB (2 x 16GB) 288-Pin PC RAM DDR5 7000 (PC5 56000) (Model CMH32GX5M2X7000C3

I just very recently (within 2 weeks) rebuilt my PC including the above components (non pertinent components not listed).

When I originally built the PC, I installed just 2 RAM sticks in the DIMM slots (above model, totaling just 32GB). Upon startup, I was only getting 4800MHz (DDR5 base speed). I Over clocked utilizing the BIOS to access the 7000MHz speed of the RAM on the XMP1 profile. Worked perfectly, no instability and no problems.

Fast-forward to last night, I had decided I wanted 32GB more of RAM (for a total of 64GB), and purchased the EXACT SAME MODEL of RAM. I plug it in and started my computer, and could hear the Computer attempting to POST multiple times, but then finally stating It was POSTing in Safe mode. I changed the BIOS OC back to Standard/Auto profile for the DIMMs and have no problems - except I'm back down to 4800MHz speed.

I did try XMP2 profile, and same results. I performed the MemTest86 and there were ZERO Errors.

Was wondering, has anyone else experienced this and does anyone have a solution to keep stability AND access the full 7000mMHz?

Thanks all.

[broncogr · Accepted solution]

You just cant add another set and expect things to work without issue.

Memory modules should be in a matched four stick set and listed on the QVL to be able to work on their rated speed.

You can start with lowering the speed manually to 6000 or less and play with voltages to make it stable

[Victus]

Hey there, I have looked and looked and looked and cannot find anywhere where RAM is sold as a 4 stick set. 

If you have the time, could you see if you can find such a set?  Preferably by Corsair. 

[Victus]

Follow up: I looked at the QVL and came to the understanding that my MB wont be able to do what I am asking it to do.  

Purchasing new RAM shortly! Thank you for your help and advice.  

[broncogr]

I am using G.Skill Ripjaws F5-6000J3040G32GX2-RS5K memory module 64 GB 2 x 32 GB DDR5 6000 MHz

Even though it is in the QVL it needs some manual tweaking to be 100% stable

[Silent_Scone · Accepted solution]

Hi @Victus 

As @broncogr has mentioned, combining memory kits, regardless of whether they're the same kit or part number isn't supported by motherboard or memory vendors.

Once you combine or mix kits, the timings, voltage and frequency programmed and validated by the memory vendor are no longer valid. This is because kits are overclocked and binned in the density in which they are sold.

See here for more information