Need help quick today, troublesome new computer...

I built this system for my uncle and aunt:
XP2500+
512mb Pc2700 (some type from compusa)
Asus A7N8x Deluxe
Radeon 8500DV All-In-wonder
Stock cooling
Antec case w/ 400w antec psu

It has random lock ups more importantly random reboots. I tested the 5v mofsets with a multimeter and got 4.80V idle, i think that is low, do any of you? I've seen it flash to 1.79V without crashing and haven't seen a voltage where it did crash yet. I'm reading 4.99 directly from the psu so I'm think maybe the motherboard's connector maybe causing to much resistance.
Also, the video card has been a real pain because of drivers. Would a vid card prob cause it to just randomly hard restart? If not any other ideas to what could be causing this, or do any of you see hardware that is crappy that could be causing it?
Installing MS Office "media content" cd seems to always do it in.

edit: all temps are fine, cpu is always <50C.

UPDATE:
I ran a bat file to make the proc usuage go to 100% and left it while checking voltages and posting this topic and I went to move the mouse and it stopped responding. so I immediately checked the 5V mofset under andto the left of the cpu and it was 4.75-4.76 and I heard in another thread under this one that crashing voltage for the person was at or under 4.79

Sounds like a 5v issue to me: I have only seen one psu that did not cause crashes with a 5v reading under 4.75 and I consider the "danger zone" to start at 4.84v or so.

Good call on the ATX connector- they are often loose and a big cause of low voltage to the mobo if the psu reads good when checked at a molex connector.

Now the problem is what to do. I'm guessing replace the mobo since something must be wrong with its connector because it was low on the 400W antec and my 420W Turbolink.

alot of people had to do some serious prep work for that mobo accoridn g to the forum over @ hard. may want to run over there and view their thread specifically for preping this specifi motherboard before even formating.

Mr.Guvernment said:

alot of people had to do some serious prep work for that mobo accoridn g to the forum over @ hard. may want to run over there and view their thread specifically for preping this specifi motherboard before even formating.

Click to expand...

link?

eh.. i had one of them.. it died after a week... and it vanished into newegg's RMA system... bah.... the whole account it was ordered on is gone... but the board OC'd nice, while it lasted LOL

sure - forgot that part

23 pages long with all posts

http://www.hardforum.com/showthread.php?threadid=568597