I'm currently crunching 12 (.0833) on my 7870 with a hexcore, HT on. Getting ~6 min per. Have mine at 1050/1250 OC and has been working fine. I do have fan at 75% manually set and has not gone over 43C.

Still rock solid at 12 HCC1's. This is a hex with hyperthreading tho. Averaging ~6 min (total time) per instance. 43C max @ 75% fan with catalist.
Praying to hear that the 28 die shrink can play with the 7870. Ready to pull the trigger today. Hate to pull on another 7870 if a 7950 would work with it,

CCC is probably your problem. I've used Trixx to downclock memory without issues. Those 2 might conflict with each other. My recommendation would be to uninstall CCC and Trixx. Use MSI afterburner instead. Better program, more features IMHO. Memory changes should work with it. (Does for me )

I'm in and ordered. TY nano and mm
@bearcat,
Catalyst is working fine for my 7870. Holding my 1050/1250 OC without forgetting. Max your GPU's to encompass all your system cores. If it's Intel it will take it. My 7870 is fine and cool at 90ish% and my Hex 980X runs under 35% unless a bunch finish at the same time. Normal for the cpu is 38ish C. From what I've encounterred, more HCC1 WU's mean more science.
Even at diminishing returns, no CPU project can do more than my GPU on a cpu core.
Watching the way the AMD 7870 works with my Hex, I'm going straight at 24 instances (12 per) when my 7950 arrives Wednesday. I wanna hear all my HW scream at least once to see what it's made of. lol. I think that the combo of 7870 and 7950 will actually be able to 'Push' my 980X. It was cranking 93% constant with WCG CPU projects with 2 NV GPUs before.... I think it's feeling neglected