stubborn memory overclock, temperature issues?

Hi,

I recently bought two nvidia 580's and thought I would try a small overclock to raise them to other factory OC's. I got the core to the planned 815 with no apparent instability, but can't raise the memory above the default (for my card) 2010.

Testing each card seperately, they are fine in furmark fine with the memory at 2030 (I haven't tried higher). Furmark throttles my cards in SLI, so I used Unigen Heaven to test them together.

Using Unigen Heaven they were artifacting at 2030, they crashed at 2025, and I noticed some of the same artifacting at 2020 (really fast flashing black shapes, almost too quick to notice).

I am ready to throw in the towel at 815/1630/2010, but am wondering if heat could be limiting me rather than the cards themselves; 2010 seems pretty low. Could the symptoms described be a product of high temps?

During Unigen Heaven the temps are in the high 70's, hitting 80 max....but they are a few degrees lower in Furmark due to only testing one at a time. Could such temps be an issue with my overclock?

Thanks

Temps don't seem too bad, try cranking your fan speed up to max speed long enough to run a few test at higher mem speeds. That should tell you if temperatures are the problem.

temps aren't bad

I dont think it is heat,I think maybe it has something to do with psu. Mine does up to 820 and 2066 stable, anything beyond that would eventually lock the computer, even after passing several 3d mark tests, I just gave up overclocking this card, just yesterday I read about some broken cards, some people even applied more voltage or the gpuz trick to disable power throttling, some guys report very little performance gains, and the risk involved is high. By the way, my temps reach 90c under vantage, at stock and oc too, i think only the fan spins higher when overclocked, No problems with this card, except sometimes VANTAGE would run very slowly and I have to finish and restart the test, I had to change power management mode from adaptive to maximum performance to solve that issue.