Black BSOD, dxgkrnl.sys+5d000 while PC is in any application or idling

I'm quite knowledge when it comes to computers, however I'm coming here for second opinions and advise to my problem.

It started about a month ago with dxgkrnl.sys+5d000 causing a black BSOD, would just randomly reset my system (all fans 100% exhaust for a few seconds, then boot back up)

My specs:
Intel i5 3570k @ 4.2ghz using MSI OC Turbo Genie. (With corsair H80 cooler)
8GB of 2133mhz G.Skill ram
MSI Z77A-GD65 Motherboard
Gigabyte Windforce x3 GTX 670
850W OCZ ZX 80+ Gold PSU

Firstly when this was happening, it only happened inside games... at 99% GPU usage. So after testing the drivers, reinstalling the OS, running memtest, reseating ram, changing PCI-E slots, changing my power extender lead from a cheap 10bar to an expensive 4bar plug, making sure both CPU and GPU temps don't go above 60c... I was out of ideas and sent the GPU back for RMA. RMA was accepted as faulty, a new one was sent out 3 days later, put it in... had some issues with PEG in the BIOS, but got it sorted and a video link was picked up. Worked fine for the last week, now the same exact problem is back.

However this time it just happens randomly, even when I'm idling. Done more stress testing on the GPU, did 10hours at 99% usage under furmark with no problems. I'm sceptical about it being another GPU issue due to the data I've gathered.

However, the system works fine with onboard graphics... nothing crashes randomly. I've exhausted all tests to no avail, I'm thinking the motherboard is faulty, however... I'd like your input please!

Here are the blackscreen viewer shots since the 13th.

Bump

Any advice? thank you.

Still seeking some advice from this from anyone who may be insightful in the community. Just want a second, or third opinion on it.

Thank you.

What a great help this community is.