Hi i built my son a new pc 2 weeks ago all was working fine then it would not boot up so I pulled the main power cable to the mother board plugged it back in and it fired up but now there is no display though maby it was a problem with his graphics card so tested it on my PC and it worked fine so.i put mine into his and still no picture not really sure what to do now could it be a faulty motherboard?
This is a very strange way to do things, pulling the 24 pin ATX cable, why not just pull the kettle lead out the back and plug it back in if you wanted to do a hard power cycle, if you hadnt turned the mains off or let the PSU discharge and then plugged the 24 pin cable back in whilst its live then theres a high chance youve fried something, at least you know its not the GPU as you say its working in you PC, are you able to test RAM and CPU in your PC too ?
I killed the LAN port my my ASUS X670e Gene in a similar way, and that really wasnt a cheap board, I had just finished leak testing my water cooling setup, powered everything down, unplugged all power, removed the PSU jumper off the 24pin atx connector and left it a couple of mins, obviously not long enough, when I plugged the 24 pin ATX power into the motherboard, I the board lit up like it had power, just for a second and I saw a flash of light at the back of the board, I just thought opps, luckily it booted fine, just a dead LAN port, sold that board as faulty and brought a new one, I also got rid of the power supply and brought a new at the same time too, that PSU had a tendency for not discharging the caps very quickly.
EDIT: Sorry to make things worse, but I just had a look at the parts you purchased, the PSU I got rid of due to being fed up with it not discharging so quickly was the one you purchased, only I had the Straight power 10 or 11 1000w version.
