Question : Problem: pc wont boot

Pc wont boot but have found if I reseat the cpu it will boot till I turn off for a period of a few minutes or more, then it wont boot up again unless I reseat cpu again.  Everything powers up ok just nothing on screen and no beep codes

Answer : Problem: pc wont boot

Sounds to me like a possible temperature issue.

Have you got thermal paste on the CPU? Even if you do it may be worth removing and cleaning up before replacing it.
Also check your fan / heatsink is well seated centrally.

Recently had a similar problem and turned to to be crooked heatsink!