What could be wrong with this computer?

[aelaan12]

I hate to admit this but I am stomped!!!

One of the computers stopped working and I think I have pretty much done everything I can to get it going again.....:devious:

Pentium IV Celeron processor not overclocked running with 512mb ram (PC2700) on an Asus P4S533X motherboard. Nvidia 64mb video board MX400 I think it is. Pretty much standard system with a CDRW and 120gb hdd (WD)

My daughter complained that the computer would not turn on every morning and she had to restart the system by unplugging the cord and reinserting it. Not something I want a child to do to get a computer going.

Come to find out that there is an issue, it seems that something is shorting out. System has a switching power supply so after turning it off and on with the little switch the fan of the CPU seems to turn just a little.
The hard disk makes an attempt to boot but never gets enough power.

So after stripping everything from the mainboard and only the video board installed and the power to the motherboard of course (power to all other devices removed) I turn the system on. At first it boots into the bios, compaining that the system crashed during previous boot. Setting the CPU to the right speed and restarting the system...... NADA nothing!

Hmmm... power supply bad? Not enough juice to the motherboard...
Power Supply replaced with brand new one. Same deal!

Hmmm something shorted out on the motherboard? Motherboard replaced with Asus P4S800..... seemed to work! Yes Seemed! Back to the same issue even with the new equipment..... WTH?

Now I am thinking that it might be the power switch on the case, as that is the only thing I have not replaced yet.....

Testing has always been done with the same case but could this be possible? I even got a UPS hooked up to the system to make sure I got clean hydro.

What about a CPU this on is 19 months old?

I am baffled!

Anyone?

 

[Xie]

So once the system is started it runs right? The problem is that you can't always get it started?

If so then perhaps it is the power switch. If your good with computers and feel comfortable running it with the side off you could test this theory. All you would have to do is "short" the jumpers for the reset switch.*

* will post instructions (with pictures) if I can find some

 

[RickyC]

The PC won't boot if the CPU, memory or graphix card is damaged/removed so it is unlikley it is any of these.

Sounds like some kind of static build up in the case or the mboard underside touching a metal part of the case. This also sometimes happens if there is a power cut or sharp spike in the power department (fun with 700 odd machines), but you have an UPS connected. Have you tested the UPS to see if the PC powers on when the UPS is disconnected from the mains?

 

[LordOfLA]

if it boots to bios its potentially not enough power from the supply - you may want to invest in a beefier PSU that can feed 25+ amps down the 12v rail andtry again (or see if you can borrow one from a friend to test before you splash out as decent supplies like that are not cheap).

Also make sure non of the drives are touching the motherbaord as that will cause a ground circuit and no power will get to anything else

lastly check there aer no broken/damaged cables.

All three of the above are the most likely cause of the PSU to engage its safetey cut off for maximum peak load at start up.

 

[lancer]

nothing is clearly wrong with the PSU did you not read he replaced it with a new one and ran it with min hardware plugged in. I would simple replace the case, it sounds to me that the pwr switch wires and/or reset wires that plug into the mobo from the cae have gone awry. I know cheap generic switch cables can easily get damaged. If you have another case in the house i'd test it out buy swapping the cases for your daughters and see if the pc works then.

 

[LordOfLA]

its an issue with peak load on power-up. Which could infact create the eaxact asme problem on 50,000 brand new cheapy powersupplies.

That peak load may bea caused by any of the things mentioned.

please do not suggest I cannot read.

 

[Tweakfiend]

nothing is clearly wrong with the PSU did you not read he replaced it with a new one and ran it with min hardware plugged in. I would simple replace the case, it sounds to me that the pwr switch wires and/or reset wires that plug into the mobo from the cae have gone awry. I know cheap generic switch cables can easily get damaged. If you have another case in the house i'd test it out buy swapping the cases for your daughters and see if the pc works then.

From an electricians angle and rewiring countless PCs that was my suggestion ......unless consistently the wrong Power sw or led leads are plugged into the wrong connector pins