My PC is dead and while i will work through a generic troubleshooting guide later today i wanted a quick straw poll of what the likely culprit is.
The Symptoms:
Sudden shut-down and slight burning smell shortly after launching 3D game. I powered off and checked it over finding no apparent damage. It then booted up as normal and ran happily for a few hours. All temps registering as normal during this time and memtest passed.
On the next launch of the 3D game the same sudden shutdown occurred and now it won't start at all. On first plugging the power the case fans and LEDs can be made to briefly twitch/light as though powered by a capacitor discharging. There is a power switch on the board and this lights when powered, but doesn't start the PC either.
I have tried a different working PSU with exactly the same result. I could try the PSU from the problem PC in another machine, it seems fine, but that feels vaguely risky unless the problem is like to be elsewhere.
Other info:
I fitted a new hard drive the day of the problems, it was working fine after this for several hours. Have tried unplugging this drive and nothing makes a difference. I mention it because the case has been opened, dust disturbed, components jiggled and hopefully nothing shorted during this process.
I don't have a second CPU or motherboard of the same type to check whether those are working individually.
I haven't yet tried a different graphics card.
The PC is a well put-together Core i5 2500 with MSI GD53 board that was 100% reliable right up to the first sudden shutdown and smell.
What do you reckon is likely the problem, any specific tests I should do? I don't really want to end up buying a replacement board and/or CPU unnecessarily if the problem is likely to be something else.