Quote Originally Posted by PiLsY View Post
Its a ryzen thing, applies to all generations. Note its only if you want to run flat timings with an odd cas latency (13-13-13-13, 15-15-15-15 etc). You dont need to run GDM enabled to use 15-16-16-16 for example.

Interesting development with my Gigabyte board, finally got a dialogue with Gigabyte support and they have confirmed that their board overvolts too, though not as badly as mine. The solution is to manually set vTT, once you have it set manually it automatically adjusts itself upwards as you increase vDDR. The issue seems to be that its auto value is 1/2 bios set value and not 1/2 measured value, so any voltage drift on vDDR puts vTT out of whack. The only annoyance is that the measured value is not 100% correct, its a little on the high side. If you have the same board as me (Aorus X570 ITX) I recommend manually setting the vTT to half your reported value in bios, this will get you close enough to run most overclocks stable. To get to the very limit you'll need to slowly tweak this down from 1/2 your bios reported value. It will only be slightly out, vTT is pretty sensitive though so if you're almost stable but not quite its worth getting it spot on to see if it stabilises you. I only need to get it perfect to run 1:1 3800mhz, otherwise 1/2 bios reported value is fine.

For reference my board overvolts 50mv idle and 65 to 75mv load for vDDR. Setting 1.45v or higher without manually matching vTT gives a no post and auto cmos clear at SPD/2133mhz memory straight from loading optimised defaults.
This is superb info mate, have that same board, also overvolts Vdimm. I did find some annoyance related to the VSOC, sometimes undervolting to 0.9v from 1.1v if set at Normal/Auto or undervolting with the offset mode. Problem is that VDDG remains in a fixed value of 0.95v.