Everything was working fine following installation of a new Gigabyte motherboard (2 days ago). The PC just swithed off whilst on idle. It wont power up now. I have checked the PSU which is working. Do I have a motherboard problem?

Perhaps, double check the connection of the front panel devices to the motherboard. Specifically the power switch and the reset switch. They have no latching mechanism so they could have become disconnected through vibration if they weren't on securely. Michael J

My very first time on a forum and an instant reply...fantastic. I have checked the switch connections on the MB (power switch)..all seems ok. I have carefully tried shorting the 2 pins on the mb and nothing happens (I am assuming this would by-pass the switch) By the way, I checked the PSU by removing the main cable to the MB and shorting the green and black wires as suggested in another forum. All the case fans etc. started.

Do you get any fans spinning when you try normal startup? Any POST beep? strip the system back to barebones. PSU, MOBO, CPU with HSF, 1 stick ram and graphics. Unplug everything else including harddrives, optic drives,any PCI cards. If it still won't post then you've narrowed it down to one or more of those parts. If it will boot in barebones then shut down and add components one at a time rebooting after each change. Post back and let us know what happens. Give a man a fish and you feed him for a day. Teach him to fish and his wife will never forgive you.

Thanks When attemping normal startup there are no fans spinning, no case lights and no POST beep and the PSU fan does not spin. The PSU test I carried out suggests that the PSU is fine (jumping the green and black wires on the PSU MB connector starts the fans and lights etc.) Is there anything else I can try before stripping things down?

no. My first homebuilt system had similar symptom and it turned out to be a dead AGP card. On another PC I had that crashed, everything except the ram had fried. Strip it down and test. If as I suspect, it still won't boot then you will need to have access to enough spares to swap out Graphics, ram, CPU one at a time for known good parts to isolate which one is the culprit. It looks like you have an AMD CPU. If that's the case it may have been damaged by thermal overload unless your motherboard has inbuilt thermal protection. Intel CPUs have it inbuilt. Give a man a fish and you feed him for a day. Teach him to fish and his wife will never forgive you.

Thanks I do have another working CPU (AMD Sempron 2400+), Graphics (64mb Ge-force 2), RAM (512mb PC2100) what order would you suggest?