z790 Hero T Force 7800 DDR5

[davis5383]

ROG maximus hero z790, i9-13900ks, t force 7800mhz 32gb ram.

when i turn xmp on, system crashes back to pc home screen. no error reports. system us custom liquid cooled. temps on cpu, gpu, mobo, and ram are all under 50c. most even lower. ram cards passed memtest. cpu set to intel limits in bios. (recent change). still have issues gaming when xmp  is on. AI overclocking on or off has the same result. OC on 4090 is off as well. ram timing matches mobo specs sheet.  bios, drivers, everything is up to date. 

[Nate152]

Hello davis5383

You're pushing the limits of the motherboard as 7800MHz is the maximum supported frequency, the cpu's memory controller could be struggling as well. Although, having a KS cpu should help with achieving higher frequencies.

What you could do is reset the bios to defaults. Enable XMP, then scroll down and lower the Dram Frequency to 7200MHz - 7400MHz then test for stability.

In the end, it sounds like you're going to have to adjust some voltages to (hopefully) get 7800MHz fully stable.

[davis5383]

do you change the timing to match a say 7400mhz timing listed on asus website?

[Nate152]

You can let the timings as they are and just lower the frequency.

If stable with a lower frequency, you can experiment with them.

[Silent_Scone]

Hi @davis5383 

1. Memtest86 will not detect all instabilities when overclocking, use dedicated memory stress tools in the OS such as Karhu RAM Test, TM5 or HCI Memtest Pro

2. Retest with XMP II as this can help and contains more relaxed memory timing subsets.

3. As Nate has alluded to maximum memory frequency qualification success often requires manual tuning or may not be possible on some CPUs where signal margins are tighter. See here for more information