Computer turns off few seconds after switching on!!

[KeeLx]

So here's my problem! I just got a new case, put everything in. Turn it on, all the fans start spinning and the led fans come on, but a few seconds later the system turns off.

 Also by the way, the PSU doesnt fit in perfectly and i manage to get two screws in (not all the way) its hard to plug in. And the computer isnt connected to a monitor or anything at the moment

Any help?

P.S by the way, my psu is brand new and i have been using it for a week and used it an hour before the case change.

[guitar_man]

when you swapped mobo to second case , did you notice any small plastic washers in bottom of old case , these are used to insulate Mobo from stand offs .try removing mobo from case and try it on an insulated surface as proof this is troubles

[KeeLx]

Small plastic standoffs? I cant see any. Only metal things that sick out and have a place for screws to go in, which i am unable to remove (for i am probably too weak...). also i didnt get to use every screw slot on the motherboard because i didnt have enough 'metal things that stick out'.

[Popeye67]

check the stand off are in the right position in new case or they can short out the board and stop it working, use a pair of pliers and use the ones from old case if necessary but dont add any extra

[KeeLx]

Its fixed! i believe the mobo connector wasnt plugged in properly or either the heatsink or something. Thanks for all the help guys!