I've bought a ASUS R9 280X Matrix Platinum Edition around a month ago and it has been working fine. I got into Bitcoin mining and Litecoin mining. I started off with Bitcoins and I've been getting some good hash rates, also I've been playing BF3 and Far Cry 3, both at max settings and it's been fine. I started to play around with GPU Tweak and overclock my GPU, I used the Burn function to save the clocks into the GPU's BIOS. I didn't really notice any problems with it but once I started Litecoin mining, it would eventually crash and I would get this white screen with vertical lines, sometimes blue with vertical lines. It also happened in 3DMark 6. I have no idea what to do now. I just want a fully functioning GPU. It shouldn't be crashing at stock clock speeds. Also, I've tried to flash the BIOS with ATIWinFlash but the problem still occurs.
What can I do to fix this problem? Also, I have a XFX 750W PSU and I don't think the crashing involves the power since I've been using it successfully before with the same PSU.