Computer Lock ups within 20min. of booting

[SPDCAD]

Computer Specs.
Intel P4 3.0 Ghz
1.5 Gig RAM
ATI Radeon 9500
200 Gig WD Harddrive

My computer is locking up lately and only turning off/on works.
The computer locks up with in 20 mins. of booting.
I have restored a good drive image of windows thinking it was a software problem, but to no avail.
I have swapped out the graphics card, no change.
Next I will try the RAM.
I replaced the Power supply in march, so I am hoping that is not the problem.

Any help would be greatly appreciated.
Thanks in advance...

Yes, I know the computer is old, but the kids need something to play games on

[Allan]

Does the same thing happen in safe mode?

[Geek-9pm]

Welcome to CH.
You say the PSU was n replaced four months ago.Very unlikely a new PSU would wait four months to show weakness. So are you sure the old PSU was really gone? What symptoms did it have?

There is a small chance the problem is a failing floppy or CD drive. Let's hope it is not the capacitors on the motherboard.

Let's suppose it is a heat problem. Is so, placing a big desk fan behind the box would extend the time until it overheats. One customer did that herself before she brought it to me. Worked fine taht way, but she got tired of the noise level.  I found the PSU fan was shot.  Earlier, another shop could not understand how to test the PSU fan.** Sometimes obvious things slip by.

Component failures can draw more current from then PSU. A hefty PSU will deliver more current and not power down until its thermal limit is reached.  This is not the same as the thermal protection of the CPU. It is a feature of high power PSU. Any cause of poor ventilation for any reason will start  thermal shutdown of the PSU.

My best guess is a bad CD-ROM drive. It happens.

** A blind man tests the PSU fan by sticking his finger in.

[Allan]

With all due respect to Geek, please just answer my question and don't worry about his post for now.

[SPDCAD]

No the computer does not seem to lock up in safe mode.

[Allan]

Open msconfig and on the General tab choose "selective startup" (uncheck all three items) and reboot. Does the problem still occur? If not, start adding items back to msconfig one or two at a time, rebooting after each change, until the problem reappears and you'll have identified the offending process. This is clearly a time consuming procedure, but it is the best way to determine if some process loading with the system is the cause of your problem.

After you've isolated the cause, do not use msconfig to permanently disable the process. Instead, if it is a service go to START - RUN and type: services.msc (then press enter) and disable the service OR, if it a program, you can download & run a simple app such as Mike Lin's Startup Control Panel (http://www.mlin.net/StartupCPL.shtml) to enable, disable, or otherwise manage startup programs.