Well, some have found that disabling the power saving features help stability. Then there are another class of SF2281 issues that I've experienced that are caused from Anvil Storage Utilities it seems, as during file deletion more of a pause is needed or the drive disconnects. That's probably not what's happening in your case as this is most likely limited to endurance testing. I found that ASUs pause wasn't long enough until I was generating more than 10000 files per loop. So that's another issue.

I know from experience that if you drop the System Agent and/or PCH voltage low enough that you'll get crashes. This is total speculation, but you could try increasing those a few notches in your BIOS.