Specs:
i5 3570k (stock speeds atm)
Xigmatek Dark Knight CPU Cooler
ASUS P8Z77V-Pro
MSI GTX 780 Lighting
Antec 750W HCG
Intel 256 GB SSD (Games)
Samsung 128 GB SSD (OS)
Seagate 3TB HDD (Media)



Problem:
Hard restarts during games/benchmarks. Computer shuts off like the power cord has been pulled and restarts a few seconds later (Event Log: Kernal Power 41(63)). It first started happening intermittently a few months ago (restart every couple of days) and has increased to the point where i can no longer run any game or benchmark without a restart. It only lasts 3-5 mins now before restarting. I have performed all sorts of tests trying to determine the cause which most likely would seem to be a heat or power supply issue. Multiple passes on memtest came back clean. Ran prime95 and intelburntest for extended periods just fine. Ruling out memory and CPU (which is at default clock speed for the moment) leaves me to the GPU and PSU as the likely sources of the error. This is where I came across some interesting. As I was running furmark to stress test the GPU i was getting fairly consistent restarts a couple of mins though. However on one run i decided to manually run the GPU fans at 100% for the entirety of the test and what do you know it makes it though the whole test for the first time in days. This made me rule out the PSU as the culprit because the system made it though the whole test just fine. So I started testing as i slowly decreased the fan % down each test. Basically it crashed everytime the fans were significantly lower than 100%. So it must be overheating right? No, well maybe. Obviously I was keeping an eye on the GPU temps as I was running the benchmarks. Most of the restarts are happening when the card is 60-72C which from my understanding is pretty normal GPU temps. With the fans at 100% the GPU stays right around 56C max. I dont think it is drivers as this has been happening though multiple driver versions. It seems like it must be something to do with the GPU, but i just dont buy that it is overheating. It doesnt throttle or drop fps before it happens it just goes down hard. I have thoughly cleaned the heatsinks and whatnot with compressed air.


I have put it a online ticket with MSI to troubleshoot the card, possibly RMA.

Any other ideas?

Thanks in advance for any consideration and help.