Computer keeps rebooting

[kahlil88]

I just built a computer from parts I bought on eBay and Craigslist, but it reboots every 3 seconds. I pulled the RAM, video card and modem from my old computer, so I'm fairly sure the problem isn't with any of these components. It's an ASUS P5K-E motherboard with an Intel Core 2 Quad Q8200 (45nm, might not be compatible with old BIOS). The CPU was brand new from eBay and the motherboard supposedly worked fine before I bought it on Craigslist.

 

[Nitestick]

i would suspect the motherboard first as the point of failure as it is not new and you yourself have not been able to verify that it ever worked. i guess you could try and get someone to update the BIOS for you as it does say you should update the BIOS for 45nm support.

 

[kahlil88]

It's just too bad I can't get the thing to boot to actually update the BIOS. I tried a different CPU (Pentium 4, 2.8GHz) that I know works for sure, but same problem.

 

[Nitestick]

in that case then i'd say the motherboard is the culprit again. are there any signs of visible damage? have you made sure all power connectors are plugged in for the motherboard and video card? everything is seated correctly in place?

 

[kahlil88]

Could it have anything to do with the 2×4-pin EATX 12v connector? My power supply only has a 4-pin connector.

 

[Nitestick]

i think that may be it. i can't be certain though as i haven't actually built a computer using a board with one of those yet.

 

[kahlil88]

I read on another forum that there are supposed to be two 4-pin connectors and both are only required for dual-core. I imagine the same rules would apply for quad-core, but I still had the problem when I tried using my friend's Pentium 4. CPU-Z identified it as the P4-520, which is supposed to be compatible with BIOS version 0201 and up.
I contacted the previous owner and he told me that it worked for him, but he had problems with certain RAM modules. My friend's RAM didn't make any difference, although I didn't try it with the other CPU.

 

[AMDSCOrPiO]

I wouldn't be so quick to blame the motherboard. Reboots like this are often signs of a weak / broken power supply.

 

[Nitestick]

my reasoning for blaming the board is it's the most likely out of the components to have not worked in the first place given the situation. though you are right, it could just as likely be the PSU.