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Low DDR5 speeds on Apex Z790 + 13900KS

Level 7


I decided to build a second high-end system for 4k gaming and a little tweaking. Because we all like tweaking right? 😉


Intel 13900KS
Asus Z790 Apex
Team-Group T-Force 2x16gb 7600 C36
MSI RTX 4090 Suprim X 
Asus Thor Platinum II 1000w
Full custom loop WC 3x360mm & 1x240mm rads

I set XMP in the bios. Nothing strange. It boots. Installed Windows and games. But in gaming I kept getting hard freezes. So I went on a diagnostic search for this problem. 

The first thing I did was running Memtest in the bios. Did a full program of 4 hours or so. No errors. Then did a mem stresstest in Prime95. Pretty much immediately a hard freeze. Now where getting somewere right? Back in the bios I adjusted the ram speed into 7400/7200/7000/6800. All these speeds will cause a hard freeze eventually. 

Tried raising some of the RAM voltages but no luck. Then I tried my old Kingston Renegade 6400 C32 kit. Got that one stable in Prime95 mem stresstest at 6600 C32.

I'm a little dissapointed because a lot of people achieve 7000+ easily on a 2 dimm Z790 Apex. I should have used my Maximus Formula Z690 instead. That one did 6400/6600 stable. Now I kinda regret I payed 1000 Euro's for a Apex Z790 + Team Group 7600 kit 😑

There're other factors playing I think?
Like faulty RAM modules?
Or a bad IMC on my 13900KS?
Is active RAM cooling needed for 6800 and beyond?
Should I buy a new A-die kit and test again?

Any tips and tricks would be greatly appreciated.





Level 8

 Hello , i have z790 gaming e and t-force 6800 and i am dont cant boot my computer , only 5600((((

This memory well work on z690 ))))



I am think need new bios !

Super Moderator

Hello, have you checked the memory controller SP score under AI Tweaker? May have a weak IMC.


1) Setting XMP II

2) Under DRAM Timing Page set Tweak Mode 2

3) Under Advanced Memory Voltages set Memory Controller Voltage to 1.35 -1.45v

4) Active cooling always recommended, a fan blowing on the DIMMs can help long term stability.

5) Check the blog here for a rundown:

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

Hello, i am try tomorrow.

My memory and cpu good work on z690)


Maybe you can show me on a picture please? 


My memory and cpu start and work on msi edge z690

Picture of what? Have you tried my suggestions?

13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

I don't quite understand what points I need to change.

Level 8

And another question, if the BIOS fails to start, will it return to its initial state? How can I avoid the requirement to install an old graphics card to run?

I’m not sure what requiring an old graphics card has to do in this situation. If the board fails training after several attempts it will POST in Safe Mode. 

XMP II is under the AI Tuner menu, same place as XMP I. The other settings I’ve outlined, you may want to use the search feature if struggling to navigate, located on the top toolbar.


13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090