When we (Madshrimps team) did the 100K+ 3DM03 run, we had a lot of issues with cold too. I see I noted -100°C in the HWBOT submission, but I remember running and re-running plenty of times at -85°C before that.

During the Campus Party 2012, Der8auer had his VGA pretested to 1200+ core, but very similar issues when doing the full runs with high CPU clock.