Hi guys,

Thanks for all the suggestions. Sorry for the slow response, I've been away without access to the computer for a while.

I ended up getting a new GPU, and the issue isn't reoccurring, which I can only assume means it was indeed the GPU having problems.

@TheDutyPaid - Trying different rails is not something I tried, but I wish I had done.. The connectors to the GPU were x1 8pin, and x1 6 pin, I remember having trouble finding spare cables for it and I may have well attached it all to a single rail. Could this have potentially been the cause? That's very interesting.

Also, I had an Asus DX2 plugged in (soundcard). However, I had tested the gpu with and without it within the computer and same result occurred. Other than that, I only had 4 120mm fans installed, along with the CPU fan cooler.

@Thorsson & lankeyphil - Unfortunately I don't have a spare PSU to test. I'm a little worried about my PSU now - along with my new GPU (ATI Sapphire R9 390) I bought a new 4k monitor, which is also having problems I'm worried may have something to do with the PSU (new thread here).