Motherboard

Check the proper seating of the processor. I've seen and heard of intermittent contacts on the motherboard where the CPU plugs in causing faulty temperature readings. Also, sometimes the power supply will sense a fault after start up and shut itself down. Check for any insulating washers that may need to be in place between the mother board and chassis standoffs. Be sure of the pin one orientation of the processor and isolate the hard drive power connections to be sure that's not causing a power supply fault.

I have insulators between the screw head and board
I have the correct pin orientation for cpu,I tried reseating and making sure but still had no success,evedn seated another cpu,at one time the board was working.
The cpu is compatible
any other ideas

The only time I have experienced the problem that you describe, was when I had a failing CPU.

The customer had just replaced the stock heatsink/fan with an aftermarket copper heatsink. in the process of mounting the heatsink, he crushed the core of the CPU (AMD Thunderbird series - no IHS). The system worked for about a week before it started having the symptoms you described. After the problem started, it continued to get worse until it stopped booting at all. When removing the heatsink to inspect the CPU, I noticed a tiny corner of the CPU had cracked... I had a spare AMD (Socket A) cpu, popped it in and all was well again.

Best thing to do is to use "known good" components (if you can), and remove the motherboard from the case and test it OUTSIDE of the case. Just connect the powersupply, install ram, install CPU/heatsink, videocard, and keyboard. Don't worry about the drives, as we just want the system to boot. Good Luck.

Hi,

As in answer 1, make sure that you do not have a large standoff or extra standoff that is touching the bottom of the board.

You do NOT want to have the motherboard fully insulated from the chassis. But you do not want any circuit traces other than the ground lines connected to the chassis.

Even though you are confidant that the power supply is good, I would try a different supply.

What about the RAM?
Many a time I have had to change out RAM that just would not work with a specific motherboard.

The video card is another item to swap out.
I have several systems where the motherboard supports 4X AGP, but you can only access the 4X mode if you first power up in 1X or 2X mode. Many 4X and 8X cards do not support the older slower modes.

From here, the only thing left to do is to inspect the filter caps on the motherboard and make sure that they are not bulging or leaking. The failure mode for the numerous lots of bad filter caps that have been used in motherboards is not immediate. In fact, letting a working motherboard set for a period of time can trigger capacitor failure.

Chas

Answer 2
I have checked the cpu,no damage is apperent to it,the cpu is installed on another board and working as I type with no error messages,the board at one time was setup,but I was getting a conflict in Windows XP,changed the ram with known good ram.Cannot understand why it fails to boot since it did before

Chas I have changed the power supply and checked the board throughly,changed memory,video card configuration should be compatible,the board is a Intel D875PBZ,the system LED will light up and the cpu fan and all other case fans will turn on.
The other thing is the reset sw will not work no matter how I changed the wires around

Point value changed by question poster.

When I mentioned insulators, I meant between the bottom of the motherboard and the standoffs on the chassis. On some of the older units, they actually had plastic standoffs, and I'll often replace the metal ones with plastic, just to eliminate that problem.

Check the power switch if it is stuck on then when you turn the system on the switch will remain on and turn the syetem off. I have seen this, also have seen a reset switch that was bad and kept rebooting the system.

This question was closed by the author