I have one in each of the non-BC1.2 groups. So there should be plenty of power. I have a fairly big fan blowing across them (I can actually touch the radiator fins without discomfort), so I don't think heat is an issue. I have the speed set to 150 MHz (want to make sure they last a long time, and not trying to run them to the max).

The problem is that each of them (happens with all three of them) will only keep running about six hours or so. After that, I see the speed slow down, and then the line in cgminer changes to "ZOMBIE." If I unplug a zombie one, and plug it right back in, it starts up, and runs fine for another six hours or so.

...

Since these are fairly new, I am checking their progress often, and catching when this happens relatively quickly, but I would like to be able to "forget" about them, which won't be possible unless they stay running for a longer period of time. Any thoughts?