Another interesting thing I have noticed is that the temps start off really high and then settle down significantly lower after running for a few minutes.
What is happening the cores hit 120C very fast and then either turn off or get the frequency turned down so it runs slower at a cooler temp.
If you want to see the fast error just connect the board to a PC with usb and run cgminer. It will show which cores are getting hot.
Regarding the ring around the cores, what would happen if that was ground down well below the chip height? Anyone tried this?
Has anyone tried immersion cooling these boards or has everyone just thrown them away?