Since getting my new PC I've gotten seemingly random hard locks while playing (also happened in loading screens) which require a reset or power on/off.

At a friends suggestion I updated my video card drivers to latest at the end of last week but then have had a lockup yesterday and another just now.

I have had a temp monitor on since I had the first lockup a couple of months back but they're always fine. GPU sits at 60 solid and the CPU barley bubbles over 35.

Forum post of new PC gear here.

Any suggestions?

Looks like you built it yourself, so you're on your own for troubleshooting. The first thing you need to know is identifying when it's happening. If it's only happening while playing Diablo 3 and not regular use or exclusively in graphics-intensive games, then you can probably isolate it to the graphics card or heavy load.

Hard locks are very often RAM related, either on your motherboard or your graphics card.

If it's locking up at any given time, it would guess RAM in your motherboard. You;re lucky to have 2 DIMMs, so you can pull out 1 of them, run normally and see if you still get lock-ups. Windows 7/8 work just fine on 4 GB of RAM if you're not encoding video. If there are still lock-ups, swap in the other DIMM. Hopefully, one of the two are causing the problem and you can return them for good ones.

If it's only locking up during graphics intensive programs, then your video card is probably the culprit. Again, you're lucky in that your motherboard has integrated Intel HD graphics. You should be able to pull your video card and run low-settings Diablo 3 without much trouble.

If you're still getting lock-ups with that, then you're kind of stuck. It's either a faulty processor, motherboard or PSU and I have no idea how you would distinguish which of those are your problem.

I second @ecocd with the RAM swap. Bad RAM happens...

I'd also update motherboard BIOS if you haven't already.

Yup thanks @ecocd and @Khan, checking RAM is a good idea. I think there used to be progs that stress tested ram for faults? Any idea's what's decent these days or is pulling a stick out the better option?

I looked at what's new with my motherboard just before posting, I'd updated the BIOS when I built the PC and newer updates seem to be about adding support rather than fixing bugs.

Just for fun I did swap my gfx cards PCI slots yesterday but no joy with the lockup again earlier today.

PS - I haven't O/C anything at all.

An old standby is Memtest. I'm sure are likely better out there now.

i will bet money that it's insufficient power, upgrade your PSU