Need help on Dead HD 4870

i just bought this 2nd hand Sapphire HD 4870 GC for gaming purpose.. at first its running smoothly on my pc (playing Crysis), then i left my PC idle and im out for dinner...when i came back, i found out the monitor screen was black..with gc-fan running at full speed. i reboot also give same result.. i've replace with my old GC and my pc works fine.. i try this HD 4870 to other PC give same black screen and fan running at full speed result..i just don't have any idea..i seek for expert here help me revive my GC..please help..

see the gpu temps.

This may be a graphics card with problem, but may also be a psu problem, what is your power supply? are you sure it can handle 4870?

if you are sure your psu is ok you should change video card, probably the problem is there;