I have an msi g45 gaming with a gtx 770, corsair memory, tx750 psu, 1tb hdd, disk drive and a i5 cpu. and It don't want to start. When I push the power switch all the fans start and a cpu phase led light. Then everything stop... Is my motherboard bad?
Could be PSU, mobo, GPU, or CPU, in order of likelihood. Or even more likely, a short under the mobo (standoff in the wrong place [you did put the standoffs in, didn't you?], a loose screw, or anything).