Imac 27" Late 2009 (i7) Only cold boots

[ALB-Repairs]

Hi, ive got a really odd system in, it only fully boots when the systems been left and is cold, As soon as the system warms up it sticks on the loading screen, Ive tested a new GPU in there and its all the same.
Any ideas?
Thanks

 

[aprendiz]

Run ASD in loop to see if anything pops up.....

 

[dukefawks]

Yeah not much else to do than GPU and RAM. After that it can be anything.

 

[ALB-Repairs]

Changed GPU and ram, Only boots in the cold, ASD only boots in the cold aswell, It runs fine once booted but just sticks if its warm.

 

[dukefawks]

Could be absolutely anything, no ideas. Would not waste too much time on this one.