Question Dead computer

[Batgammon]

Hi so my computer decided to die suddenly. We narrowed down the fault to what we thought was the motherboard GA-B75M-D3H so i ordered a new one from China. Three months later i installed it reconnecting all the leads etc only to find the computer is still dead. I've checked the PSU by connecting the green and black terminals together and the fan turns on but when its connected to the motherboard no fans working. Ive changed the cmos battery also just in case. Any ideas? I noticed that the paste between the cpu and the CPU fan is eroded but cant think that would cause the CPU to burn out (socket lGA 1155) and even if it is wouldnt the psu fan turn on? Any thoughts on this? Also posted this in components forum as i wasn't sure which one applies

 

[drivinfast247]

How did you swap motherboards and not remove the CPU cooler?

 

[Batgammon]

When i swapped out the motherboard i moved the CPU and the cooler to the new motherboard. The question is whether a dead CPU would in fact stop the motherboard from working ie the CPU fan and the PSU fan - i cant see that it would?

 

[Batgammon]

ps i bridged the two pins for the power switch on the motherboard just in case it was the switch- made no difference

 

[Batgammon]

Found out it was a faulty i/o module. Must have been a short on one of the USB sockets which actually prevented my computer from starting!!