77ºC is too high. The fan should always run at high speed.
"gpu-fan" : "70-90",
Post screenshots of GPU-z while mining, both tabs and also of speedfan.
Are you undervolting the card with VBE7? Since you can't read the VRM temperature, I hope you are.
That said, there are defective Corsair PSUs in the market
My card was running with 77°C while fans where at 100%.
I undervolted it using VBE7 to 1,094 and they run at 71°C max now with fans somewhere between 70-85%.
Haven't seen a crash since then but 77°C on the GPU shouldn't cause a shutdown so i can't really say which component might be faulty...
http://imgur.com/BWcy7yK,lcmRu0jhttp://imgur.com/BWcy7yK,lcmRu0j#1Not that it helps, but I've just set up my first ever card (R9 280X) using corsair AX760 PSU, and have the same shut down issue.
I found that if I remove the Intensity value (-i) from my cgminer cmd file, it doesn't shut down.
However the hash rate is shockingly low at 16khs, with and without the -i value specified.
I'm a noob at this and just put it down to me not doing something, so immensely interested in this thread.
Regards
Rob
I sometimes get 10-20kh/s i can fix that by launching a game in fullscreen mode and close it.
Doesn't always work right away but at the second try it works most of the time.