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Should bios Auto-train SA voltage to different values at the same setting? Affects DDR5 stability.

1TM1TM
Level 11

I tried to train XMP speed+400. XMP is off (Auto). Set only CPU VDDQ (TX) 1.2V, VDD VDDQ and CL+2 per XMP. All else auto. (2x48GB dual rank 24Gbit chips hynix) 

What I observed:
It (z790i, Bios 1501, ME 2307v4 hot fix 30 same as latest Bios 1801) auto-trained SA to be 0.85V. At XMP+200 that was ok, but at XMP+400 it caused errors in the built-in Memtest86. After a reset (by case button) bios auto-re-trained SA to 1.29V. Now memory test in Bios Memtest passed, and ycruncher-VT3 passed.

Shouldn't the SA auto-training table be fixed to target memory and speed? image.png
This variation was unexpected, and adds uncertainty to DDR5 stability. Please ask the development team to double-check the SA auto-setting routine.

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2 REPLIES 2

Silent_Scone
Super Moderator

Hi,

Are you sure you hadn't booted into safe mode? I've not once seen this behaviour.

Once parameters are changed, please note that the newly input/saved values won't apply till the system has rebooted.

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

Pretty sure it didn't boot into safe mode: the tREFI is 6000+ (on Auto) and in safe mode it is 3900.