Could be the power module on the board is fried.

Try remove the battery, AC adapter and holding down the power button over 15 seconds to discharge and reset the laptop.
Then connect AC adapter...

Could be the HDD controller onboard causing the problem.

Unplug the AC adapter and the battery.
Try remove the HDD and the removable devices, then holding down the power button do not let go for...

Try reset the Bios.

If the CD cannot boot the computer, seems the mainboard is faulty again.

Try unplug the AC adapter and the battery, holding down the power button over 15 seconds to...

Please advise what type of PC and more details.

Any beep sounds, what is the monitor LED status...etc

Replace the broken wire and see if your laptop POST.
For me, I would say, probably not since CPU already overheated, maybe the mainboard not letting the PC to POST because it detects the wire is...

Do you have a known good HDD?

Try run from DOS the fixmbr and fixboot command to fix any boot file errors.

Check the PSU as well.

Hope this helps!
Bill

Check the power connectors and make sure there is no dust stuck the connection as well.

Reseat CPU and RAM.

Hope this helps!
Bill

This problem seems the same as the PC keep rebooting when clicking on the logon logo in XP.

Reinstall the XP works, the system has been infected by the virus and the XP needed to be reinstalled.
...

Try swap the RAM in different slot or just use 1 RAM only if there is more than 1 RAM stick.

Check CPU fan for overheated issue.

Get to the HP web site and download the latest chipset driver,...

try use RAM on other RAM slot and reseat the CPU.
Check the monitor VGA cable connection as well.
If possible, use the monitor on other working PC and see if the monitor is ok.

Hope this helps!...

I wonder it the monitor ever been tested on other working PC.

Sometimes the semi faulty RAM or oxidized RAM slot may cause no beep but no screen output and shut down.

Hope this helps!
Bill

I would suggest try check the keyboard if there is any stuck key(s).

You may also try remove all removable devices like DVD, external KB/MS, PC cards, AC adapter, battery..etc.
Then holding down...

I would suggest you reseat the CPU.

Also there may be more than 1 connector from the PSU that you need to connect to the mobo.

If the PC shutdown in 1 second, I believed not a overheat problem....

So another faulty mainboard?

without Ram, the system should beep.

Hope this helps!
Bill

Sometimes installing the new hardware may cause the system not to recognize the original hardware.

For me, I reset the laptop first by doing the following steps:

(1)power off and remove AC...

I have seen a lot of laptops with similar problem causing by the power management part failure/ electric shockand thus caused the damaged to the system chipset.

Most of the time, the shocked power...

Try clear the CMOs on the mainboard using the jumper or removing the battery.

Use the original heatsink that comes with CPU and see if that works!
Hope this helps!
Bill

try swap the RAM on different slot.
reseat the HDD cable may help.

if blinking cursor appear before the windows logo, the MBR may be corrupted, just boot to the windows CD, and run the recovery...

Try boot PC and pressing down the F8 key and select the Last Known Good Configuration from the boot menu.

if this still not working, try safe mode then.

I would suggest reseat teh CPU and RAM, when the PC POST, reset the BIOs to factory default.

Try not to set the RAM speed too high, your mainboard may not work steadily.

Hope this helps!
Bill

Check the mainboard if there is any leaked capacitors.

Hope this helps!
Bill

Hi sgamble,

"video card overheating"

Yes, this may be a issue as well.

Check the fan if there is any on the video card.(some may not have the fan design)

If the slower fan with dust...

I would use the other known good HDD to test the system.

Or simply remove the jumper on your HDD to let the system recapture the HDD again.

Before we do have the freezed PC replacing the HDD...

Seems you have done a lot of software part to troubleshoot. If reinstalling the windows still causing the problem, I wonder if you have installed the latest chipset driver for your mainboard and...

Try Last know Good configuration option.

After pressed the power button to power on the PC, press the "F8" key and there will be a boot manual. select from the Last known good configuration" and...

Try pressing down "F8" key when PC powering on, then select from the boot manual, "Last Known Good Configuration" and hit enter.

Also, have you try use windows CD to boot the PC?

Clean the CMOS...