Computer will only boot up after power connected for 5 minutes

Neil_W

Honorable
Jan 30, 2013
3
0
10,510
Hello,

PC, 4 years old, quad core Intel, ASUS P5QL mobo, HEC 550 W PSU, worked perfectly but now is completely dead until the power has been on for around five minutes. Then it boots normally and again works perfectly apart from not returning from sleep mode. Will a new PSU or mobo solve the problem?
 

Neil_W

Honorable
Jan 30, 2013
3
0
10,510
I have replaced the cmos batery but there was no effect. I suppose there could be a duff capacitor somewhere.