PC keeps restarting HELP!!!!

[mykeon]

:( guys im new here,
But I really need your help.

My PC keeps on restarting, used to be on 6 to 11PM. So I thought maybe it was just a power shortage. When it restarts and reaches the log-in screen but restarts but now it restarts even before the booting starts. It even restarts besides 6 to 11PM.

Here are the symptoms:
Event viewer doesnt show any errors"System or software"
PC keeps restarting even before reaching ASUS logo
At times my display is crashed
At times cannot detect HDD Sometimes I turned on the PC but there's no display on the monitor but the PC is on, and I've notice that when there is no display on the monitor, I don't hear the beep warning sound.
*I've checked connection entirely and it's secure*
Then somehow it works fine again, but again it starts to restart.

Ive asked some friends about it and here is what they suggests that's causing the problem.
Power Supply
Dead Battery
Video Card
Processor is dying on me :( wahhh...
Im not sure which part is causing the problem since I don't have a spare PC to checked each part. Maybe you guys experienced something like this. I need help on how to identify and troubleshoot this problem, thanks.

Here's some system Info
OS: Windows XP SP2
Processor: 1.60GHz P4
RAM: 386 still using PC133
Video card: G-Force FX 5500 128MB
MB: ASUS P4S133
BIOS: Award Medallion BIOSv6.0

[Spearball]

First off, try checking your system temps in the bios. Post them here. Second, try starting up your pc with another video card. Seeing that your display is sometimes crashed and sometimes the display doesn't even come on has probably something to do with your gpu.

[mykeon]

Sorry it took me a long time to reply, i forgot the sight where i posted my forum. anyways I've tried using other VGA card still its the same. Right now im using my PC " the one that keeps restarting" Here's the latest symptoms.

By this time about after 12 mid night my when I boot my PC, the PC is on but there's no display after about 2mins it boots. Then detects everything else like nothing is worng. And I could use it until 7 A.M. and then it restarts again and again.
I thought it was my Hard disk, so I remove the HD from the PC but still it restarts. The oly thing left without the HD. Are the Video card, of course the motherboard. 1 ram 64.

2 things im trying to look at where I could not tell if I don't have another PC to try i on.
1. Power supply
2. Motherboard

Im thingking its the either of the 2.
my budget is low so I just can't by any of this two without knowing whats really causing the trouble. SO I need help which is which.

[mykeon]

And Spearball, Ive looked at the sys temp it's all in good condition, or in minimal temp. Nothing is wrong there. Im really confused it's the first time i have encountered symptoms like this on my PC, I can't pin point what is really wrong.
Ive tried reformating the whole HD and installing a new OS, WIN XP. Stil no succes. Tried downloading avast anti virus, it detected 2 trojans but after its still the same. PC keep on restarting over and over again.

here are the 3 questions that's on my mind now.
1. Would a defective HD do this to your PC "restarts PC"?
2. Would the power supply be defective, and can't supply that much power?
3. or could the Motherboard be defective, that at time it goes normally and then abnormally?

[Whyzman]

Hold old is the system?? I'm guessing by the RAM that there's probably a good reason to suggest replacing the motherboard button battery. I'd start with the battery...

[mykeon]

It's about 4 years now, I've already replaced the button battery. Hehehe...It could really be the Motherboard though. But Im guessing if I would have to replace the motherboard I might as well replace the whole PC hehehe.

[Whyzman]

Which OS are you running?