ASUS MOD BIOS ，Phenom II X3 @ Phenom II X4

[iddqd]

having strange issues with this setup
M4A78T-E (with mod bios)
PII X3 720 BE
this RAM

it seems to be getting less and less stable over time.

I was running it at at 2.8 ghz @ stock voltage for a couple weeks, with ram set to the 1600 mhz divider (@ 8-8-8-24, 2.0Vdimm). Notice how this ram is rated at DDR1800 9-9-9-24, 1.9Vdimm. In the beginning, it was memtest86+ and prime stable. A couple weeks later, it corrupted the hard drive. And fails to POST.

Turns out that one of the memory sticks is defective (errors in memtest86+ now at pretty much any frequency). Strange.. Anyway, Now with only 3 sticks it has cold booting issues. If it does actually POST, it's pretty stable. Although there's no way I can get it to POST with the 1600mhz divider now. It sort of works with the 1333mhz divider. Now, I need to up the voltage on the CPU to 1.375 (from 1.325) to even get it to POST 1/2 the time. Should I RMA the board? Is there another AM3 DDR3 board I should try? It's still failing to POST half the time. If this goes on, it will eventually not POST at all.

E: also, using the 1600mhz divider results in a cryptic DQS error. Anyone else getting this?