Asking about stable XMP on quad channel DDR5 Z790 Asus TUF Plus Wifi

[Tweakerstarter]

Hello fellow Asus users,

I am currently running into issue of not passing RAM test when boot with XMP on. I am running on Dual Chanel with 2 identical Gskill kit at 6400mhz the only different is one of the memory kit if 32Gbx2. I could not OC the RAM to upper than the system auto setting  non XMP 4200Mhz. Everytime I turn the xmp on for whatever XMP I chose and even with the SVID DRam voltage set up from basic 1.4v to 1.41 or 1.42 it would not boot and pass the memory test, if I restart then boot I got BSOD and Unexpected Kernel Mode Trap error. I would not know how to set this to work and how to run 4 RAM at 96GB to work. If I only install in Slot A2 And B2 it would work normal with XMP on. Additionally to boot the pc with the default RAM speed I have to clear the CMOS by removing the battery to make 4 RAM sticks work.

Ps: I am using the 14900K with newest BIOS update on 10.24.2024 from Asus suppory site

Could some professional or acknowledge people know how to make this work I really appreciated that.

[Nate152]

Hello Tweakerstarter

You're having issues because you're combining two memory kits.

G.Skill states not to combine memory kits, this will cause instability or system failure.

All four sticks may work, but you'll have to settle for a lower frequency.

[Tweakerstarter]

Thank you for the fast response, I did miss out this info, I wonder if any kit run with 4 of DDR5 RAM with XMP on

[Nate152]

You're welcome

The faster four stick memory kits are 64GB (4x16GB).

Doing a quick search,  G.Skill's 64GB memory kits are 2x32GB kits, I don't see any G.Skill 4x16GB DDR5 memory kits. They stick with two sticks because four sticks puts more strain on the cpu's memory controller.

There are other brands that have 4x16GB memory kits, an example is the corsair dominator titanium 64GB (4x16GB) memory kit.

64GB 6400MHz CL32 is pretty aggressive memory kit and may need manual voltage tuning.

DOMINATOR TITANIUM RGB DDR5 Memory | CORSAIR

[Tweakerstarter]

I honestly don't mind OC RAM I just could not find the detail guide for 4 RAM stick on this motherboard, I did research and figure out some people said the TUF does have problem with XMP sometimes. So for dual channel RAM it is pretty easy to find but 4 of them to work stable I don't think many people could do that due to the CPU memory controller itself. I just need a lot of memory on RAM since I always use around 60 -70% at 96GB.

[Nate152 · Accepted solution]

I see, you must be doing more than just gaming.

If you use your pc mainly as a work pc, higher speed isn't as important. So, you could keep what you have and run with a lower frequency.

I have the ROG Strix Z690F Gaming WiFi motherboard with the i7-12700KF cpu. I have Kingston Fury Beast 16GB (2x8GB) 6000MHz CL40. With the adjustment of five voltages, I'm able to overclock it to 6200MHz CL36.

Without enabling High Dram Voltage Mode, the highest you can go with the Dram VDD and Dram VDDQ voltages is 1.425v - 1.435v, to go higher (which I haven't done), you'll have to enable High Dram Voltage Mode. Some aggressive memory kits set these voltages to 1.45v and some users run these voltages up to 1.50v, so you can go a little higher if you want.

The five voltages are on the Ai Tweaker page in the bios.

To see what you can get with acceptable voltages, an easy way to go about it would be to:

1) Reset the bios to defaults (F5 key)

2) On the Ai Tweaker page, enable X.M.P.

3) Scroll down to Dram Frequency and change it to 5200MHz.

4) Dram VDD voltage  - 1.420v.

5) Dram VDDQ voltage - 1.420v

6) CPU System Agent voltage - 1.28v (Some cpu's show instability if this is set too high)

At the bottom of the Ai Tweaker page click Advanced Memory Voltages

7) IVR Transmitter VDDQ voltage - 1.40v

8: Memory Controller voltage - 1.40v

9) Hit F10 and enter to save and exit.

If it boots with 5200MHz, you can use this as a starting point and try the next highest frequency. These are the same voltages I have set for my daily overclock.

[Tweakerstarter]

Thank you for your guidance.

This is a very good headstart for me. I read reddit and they event put CPU system agent voltage to 1.35v to make it stable at 1.45v with High DRAM voltage I think. I will try with 1.435 without enable to see if it works first.

I will update what works after

[Nate152]

 X.M.P. may set the cpu system agent voltage to 1.25v., 1.28v is a small bump. Would try it here and see how it goes, you may be able to go higher than 5200MHz. You can push a little harder with the voltages at your discrepancy. 

One thing to keep an eye on when overclocking is temperature, up to 1.45v - 1.50v should be fine without needing a fan.

I use HWinfo to monitor clock speeds voltages and temperatures, it shows the five voltages you adjust and the temperature of your memory. With memory, try not to go over 50c as this can cause instability with some memory kits.

It will show your memory at half speed, at 6200MHz mine shows 3100MHz, temp at idle is 31c.

CPU System Agent voltage = CPU VCCSA (Mine is set to 1.25v)

Memory Controller voltage = IMC VDD

Click the pic to make it bigger.

[Tweakerstarter]

Thank you for your recommendation

I undervolted my cpu so it produces less heat at 5.5Ghz. And my memories are only around 35 - 40 on load so I would not see it will cause problem.  I will try to stress test on Karhu to figure how well it goes if it actually boot. 

[Tweakerstarter]

Update on the issue. It stuck on the yellow light after I applied these settings:

1) Reset the bios to defaults (F5 key)

2) On the Ai Tweaker page, enable X.M.P. and I chose XMP 2

3) Scroll down to Dram Frequency and change it to 5000MHz.

4) Dram VDD voltage - 1.45v.

5) Dram VDDQ voltage - 1.45v

6) CPU System Agent voltage - 1.35v

At the bottom of the Ai Tweaker page click Advanced Memory Voltages

7) IVR Transmitter VDDQ voltage - 1.40v

8: Memory Controller voltage - 1.40v

It would not even get to the BIOS screen or gave me a warning. Only when I remove the RAM to 2×16Gb it said I was POSTED and have to enter BIOS to do F5 again. I probably got unlucky with the sillicon or just 4 DDR5 at motherboard supported 4800Mhz speed is a luxury thing.