I typically run folding@home 24x7 from have three 580s doing such work. One of the cards has a little problem. At the beginning of the summer as temperatures started ramping up I left a single gtx580 machine crunching in the garage, as I normally do, and when I got home I was greeted by the FAH console reporting it had rejected several work units for the GPU being unstable and when I pulled up precision X and looked at the log it seemed the thing had pegged itself at 98degrees C about 6 hours before I got home and kept downclocking the GPU to 405MHZ and reramping up to the OC speed of 900MHZ core (1.088v) I down clocked it, and the temps from that point forward were never the same on the card.
First order of business, since it was stable, I removed the old TIM (flaked off and had a consistency of dry graphite lube, no smearing possible)and replaced with artic silver 5; I've had the same (big)tube since 2005. The GPU didn't return to previous temps and I had to run it 40mhz lower to keep it out of the 90s but it did run stable. After about three months of usage (occasionally shutting down client and PC, restarting to "cure the AS5), the core temp started creeping up to overheat condition. When I removed the vapor chamber I found that perhaps I had just enough TIM. Coverage was complete on both the vapor chamber and GPU and there was very minimal squeeze out around the perimeter of the GPU but the squeeze out and between the two pieces was 100% consistent. It seemed to me each time I had had this vapor chamber off that there is definitely an engineered distance between the chamber and the GPU IHS, making the AS5 thicker (though perfectly consistent in depth and coverage) than I had ever seen on a CPU IHS. Also, something i had never seen in years of using AS5, the TIM was browned throughout, particularly on the edges and way way more tacky than I have ever seen.
So I removed, cleaned, lapped, replaced. A friend of mine owns a PC shop so I scored a new stock tube of AS5 as the friendship tax and between the two I got a 3c drop over what the AS5 new baseline was but a few months later and here we are again, temps are creeping up. Doing some research I have determined what the non TL;dr crowd probably had known and that is AS5 is not the best performing compound out there, especially where a lack of clamping force due to the observed distance between the IHS and the vapor chamber is concerned. I am guessing that buying a tube of Prolimatech Pk3 is in order. My guess is that AS5 is just overwhelmed by the requirements of therm dissipation for the GTX580s.
So is some Pk3 in order? Will it really permanently remedy the thermal creep problem i have? Should I consider another TIM? Thanks.