PC powers but doesn't POST

[Jfattu]

I have an ASUS P5NSLI MB, Intel Core 2 duo E7500 500W PSU. I've already reset CMOS and even replaced the MB battery. I've powered up with one and even none of the memory cards. I managed to get POST to show up ONCE and it said Almaty about being in safe mode that there's a problem with the memory or CPU setup so I hooked up the keyboard and went into BIOS but it wouldn't let me change anything so either the keyboard or something related stopped working midstream. After a restart it went back to it's old way of powering up but no beeps no POSTing. Everything was fine until today except for one other time it did similar but a quick reset fixed it.

 

[pjmelect]

The fact that it sometimes posts would make me think that the power supply may be faulty, try a new power supply to test. If you do not have another power supply to hand then try disconnecting everything from the power supply that is not essential to post such as the hard drive, CD drives, use the motherboard graphics etc.

 

[tsnor]

may try these steps: www.tomshardware.co.uk/forum/261145-13-read-posting-boot-problems

Std debugging is to pull parts until it POSTs consistently. +1 for pjmelect's pointing the finger at the psu. do you have another you can swap in, say from an old computer. All you need to POST is the two power connectors to the MB so you can leave the old PSU in place and put the new one nearby...

 

[Jfattu]

It turned out to be the motherboard. I replaced the PSU first but it didnt seem to help so I just replaced the mono. Its too bad with the limited options for socket 775.

 

[Jfattu]

Best answer selected by Jfattu.