TRD mem timing too tight can cause 3d apps to 101 BSOD even if you are completely stable at desktop testing.

Sounds memory or memory controller related to me.

You can try increasing qpi/dram to 1.25 and dram to 1.65 and see if that helps. If so you have your answer, if not its something different.

Couple of things there for you to try anyway. Good luck, I know how frustrating it can be hunting a stock clock instability. I firmly believe its related to memory in some way though.