Computer unable to start fully (most of the time)

[Prophious]

Hi, I'm new here and I hope that the people here could help

system specs:
BFG NVIDIA nForce4 Ultra
AMD 64 4400+ x2 w/ zalman 9500 heatsink
2GB ram ddr 400(2 x 1gb)

850 watt power supply
(+3.3v 28A, +5v 30A, +12v 70A, -12v 0.5A, +5vsb 4A, max combined load on +3.3v and +5v is 180W)

4 hard drives (all on SATA)
2 500gb
1 400 gb
1 80gb

dvd DL writer drive
xfx nvidia geforce 6600 gt( swapped with a bfg nvidia 9800 gtx)
creative x-fi sound card
windows vista ultimate


the problem is that my wife's computer is stalling in a sense when she starts up it loads bios most of the time then the monitor goes into power save mode(this is all before windows starts) and the keyboard has no response and the only out of it is restarting the computer but the cycle starts again just get past bios then the monitor goes in to power save mode again

also sometimes when she is able to get fully in to windows it dose stay functional most of the time but there are some times that the monitor goes in to power save mode and there is no response from keyboard or mouse

and there are sometimes we go out for a bit(1-2 hours) and it may or may not work after the computer goes into power save mode, when it doesn't work the mouse and keyboard have no response

what i mean by no response for the keyboard is pushing the num lock, cap lock, and scroll lock keys, the lights on the keyboard do not change at all(if it was on it says on, if it was off it stays off)


my thoughts about it are that it could be one of 3 things:
motherboard
memory
cpu

things that have been tried so far:

1. swapping out the monitor
2. swapping out the video card
3. removing everything from the case piece by piece, thoroughly cleaning each piece, and putting all back together piece by piece
4. replacing the bios battery
5. swap power supply


Edit: after the #'s 3 and 4, things tried(both at the same time) the computer has had an up time of more then 24 hours in a row and has successfully resumed after power save mode, so i think if it happens again i will repost back here

Edit 2: after about 3 1/2 days it finally started to do the same thing that it has before, now on the 5th day it wont even get beyond the bios, about 5 to 10 secs then it happens, i did try to swapping the power supply and it still did the same thing, the next thing on the list to do is clean the cpu and put new paste on it, then if that dosent work i would swap out the cpu, if that dosent work then take out 1 memory module, then swap with other if still not working, then finally i know that it is the motherboard(for some unknown reason, as far as checking the hard drives, i really dont think that that may be the problem, since there is no noise and all drives show up when i can access the bios

 

[Tmagic650]

This could be caused by a failing hard drive too

 

[Prophious]

Tmagic650, that would be something i would have thought about but the thing is that sometimes when i when in to bios it did the same thing as before, it was like the monitor went out and the computer was still on, so thats the reason for swapping the video card, but before that we tried swapping one of my monitors with hers and it sill did the same thing, i read in a forum somewhere that it could be dust, well she cleaned the computer while it was still together and it worked for about 4 hours maybe a little more, in that same forum they said something about the bios battery so i had her take her whole computer apart piece by piece(well the cpu was still in the motherboard) and at that time i told her lets try this(the bios batter replacement) so since i had a spare motherboard around, i replace the battery and then she cleaned every contact with alcohol and wiped with a cloth to make it dry, then she reassembled the computer, and so far it is working for over 24 hours in a row(she wanted to download something so she left it on all night), and has not turned it off yet, and there were no resets due to the, lets call it a power bug

 

[tw0rld]

How about a failing Power Supply? This seems more plausible. Do you have another Power Supply Unit that you can swap for the one now in use?

 

[Prophious]

power supply swapped and still same thing happens

 

[raybay]

What happens when you try a basic install: one hard drive with one operating system, one power supply, 2 GB of GOOD memory (not value ram or some other limited modules), video connection, one optical drive.
Does it also stall with this simpler system? I would then change the memory to the best you can find, and replace the CPU fan.
Note that 850 watts means nothing unless the power supply is a quality brand and model. A top 350 Watt power supply can deliver more usable power than some 850 watt power units.
We always suspect memory, ;power supply, and fans... the cheap stuff... then the hard drive that is not a Seagate or Western Digital when flakey stuff is going on.

 

[Prophious]

the original power supply was very good i think(read specs at top) and the replaced power supply originally had no problems running my wife's computer system

also i forgot to mention in the system specs that the cpu heatsink fan is a zalman 9500, and that the 4 harddrives that are installed are 3 WD and 1 seagate (the OS dive)

will be trying the simple computer setup soon, have to get thermal paste to put on the cpu

i'll repost back if nothing changes

 

[Prophious]

well it turns out that with even a simple computer setup (1 hdd, 1 cd drive, 1gb memory, onboard sound) still does not work and its worse sometimes i get the bios beep but not mostly i dont, i had nothing connected except the monitor(no usb, no keyboard or mouse just nothing outside the computer connected except the monitor and no hard drives and no cd drive) and same result, i changed the cpu and still the same thing, now i'm faily certian that it is the motherboard but why would it work sometimes and then work for 5 sec then down to nothing, i really dont get it

 

[raybay]

Now that you have proven to yourself that it is the motherboard, get another motherboard that will accept the CPU you now have, and get back to normall... There are lots of them available at a good price.