Win7 PC locking up

[2Drunk2Funk]

When I play a game and I guess, stress the system more, it completely locks up. This can happen 2 hours in, or 5 minutes in, sometimes fine for days... recently however, it seems to be occurring constantly

I have cleaned the inside (it was dusty!) and checked the fans are operating on the CPU and GFX, they look fine and no apparent over heating problem.

I installed SpeedFan to see if I can see the temperates in Windows, rather than through the bios. Image below is a snapshot under browsing conditions with PC up and running for an hour.

CPU/GFX look ok, I have no idea what Aux is but it looks to be a problem??

Any ideas, and other things I can try?

 

[2Drunk2Funk]

Enabled logging with speed fan and while playing game the GFX was beeping as I set it to if the temp went over 58, it hit 60, is that too high?

Card in sig, I took it out, cleaned it as best could, fan works etc but getting that hot with the side off.
Never used to have a problem when on XP, not sure if that is it but not crashed today having it with no side on.

Been happily working for couple years though so rather strange.