1 The front panel on/off button works.
2 The CPU fan and front Panel lights come on.
3 The lights on the keyboard are strobed once.
4 The monitor makes starting noises, then says "Shutting down in 5 seconds"
5 The hard drive makes a very short shudder, like it is probed, but doesn't start a boot process.
6 The the video card was replaced with a known good one.
6 No amount of pounding on any keys gets into Bios Settup.

From those symptoms I decided that the CPU must be working, leaving memory and motherboard to take the blame.

So I replaced the memory with known good memory, twice, which worked when reinstalled in the donor machine.

Then I bought and installed a replacement motherboard.

And it still just turns on the fan and lights.

Questions:
1 What can cause this besides the CPU, memory and motherboard?

2 Do the above symptoms indicate a working CPU, or am I passing it too quickly ? (It is a Pentium 4, so I don't want to replace it on a lark. But will have to if nothing else helps.)

3 Does anyone else have any experience with this kind of symptoms, and remember the solution that worked for them?

4 Does anyone have any suggestions for what I might try to get more clues out of it ?

Bad PSU maybe?

Thank you. I had not thought of that. Last week I had a system operating flakey, and it turned out the be the 5V supply running at 4.75V. I replaced the power supply and all was well.

I have a spare power supply here. I'll put it in.

Unfortunaltey I don't have spares of Intel parts, just AMD all over the place. So my one and only Intel system is mystery meat.

I'll let you know if the power supply fixed it.

Well the results are in.

I replaced the PSU and it did the exact same thing.

Does it havea CD drive you can boot from?

Have you tried a different HDD/cable?

Try remove all the components including the processor and memory. Then power up the computer. If it beeps, then you know the motherboard is working. If it does not beep, the motherboard or power supply is bad. The processor might be going.

A diagnostic card may help you find out the problem better than just guessing.

I removed everything, including the memory and the CPU and turned it on.

The green power LED came on, but no beeps.

So just as a check, I did the same thing to the computer I am now using. I got the same result. No beeps, just the power LED. Therefore I cannot convict the motherboard in question because it failed to beep.

Yes, a diagnostic card would be better than just guessing. Anything would, including running tests and asking for help.

I didn't think we were guessing.

NO!

Without processor the motherboard won't beep! You can take out everything except the CPU.

Try it again with just the CPU, no RAM. If it does anything at all and then shuts down, it might be a thermal shutdown. P4 does that when it overheats. It might be overheating due to lack of cooling or it might think it is overheating. In the latter case the CPU is unusable.

If it beeps and then burps it indicates no RAM present. Insert RAM, and proceed from there.

jlinkels

Thank you jlinkels. It makes more sense that I am supposed to leave the CPU in, because what else will execute the code that tests and beeps.

So I put the CPU back in and tried it again.
It still did not beep. There was just the running of the CPU fan.

I believe it has an AMI BIOS because it has an American Megatrends chip on it. None of the AMI beep codes lists no beep at all. No beep at all indicates that it stop before it can get started. But when I have other things attached, it probes the keyboard lights.

I concluded it was a dead motherboard, so I ordered a new one. This is the results from the new one.

I guess I now have to suspect that the CPU is not as innocent as I had supposed.

I will try to find someone who has in intel system with a P4 who will let me experiment.

And no, its not shutting down due to overheating. It runs until I turn it off.

Its the ability to turn on and off by the front panel button that had me convinced that the CPU was OK.

So let's summarize:

-You have a new mainboard
-The only thing in common is the CPU, you don't have any memory
-When you start, the keyboard lights are strobed
-It doesn't beep
-It runs until you switch it off
Is that correct?

Is keyboard light strobing a result of a functioning CPU? Dunno, it might be a startup sequence of the kbd itself. Can you check that by starting the MB without CPU? Do the lights strobe?

There is one other thing in common: the kbd Did you replace it or remove it while booting?

Switching on and off is a HW issue, it should switch off without a CPU as well.

If it is not the the kbd hanging the machine, I bet for the CPU somehow being defective.

jlinkels

Thank you jlinkels.

Your summary is correct.

I just powered it with the CPU removed, and the keyboard lights turned on briefly. They did they same thing they did before, but I am no longer referring to it as strobing, because without the CPU they obviously were not strobed. As you have said, it must have been merely a function of the keyboard being turned on.

Without the CPU I was able to turn it on from the front panel switch. I had the CPU fan plugged in so I could see when it was turned on and off. Although it could turn on from the front panel, it could not turn off from the front panel. That is, holding it in for four seconds no longer had anything to count off those four seconds, and it just continued to run until I pulled the power cord.

Turning off from the front panel still looks like the CPU was working, but it isn't conclusive. To be conclusive, I need to insert that CPU into another working system and see what it does.

What I suspect I am going to find is that it does indeed work, and that I have just bought a brand new dead motherboard from Ascendtech. This is my first purchase from them, and I had great hopes to continue, as they stock older components that are hard to find elsewhere.

Basically what I am doing is providing a free repair service for friends and family. In this case that has turned out to be one of my wife's co-workers. She has paid for a new motherboard, and now I can ask her to pay for another one, or eat it. And of course I will have to eat it. That's the price of providing a free service

Therefore when someone here provides a free service of their time and attention, I appreciatie it very much, whether it turns out to be a hole in one or not.

And the other thing I do, with permission, is return the repaired system with a Linux virtual machine installed. Then they can try out Linux with their Windows system to fall back on any time things get a little sticky. So far everyone has grown to love it.

I feel sorry for you.

Until 2000 or so I was running my own humble computershop. At that time I was worried about the ever changing specifications and interchangability of components. Especially Intel was good at this. Socket 5 went, Socket 7 came, then Slot A, then socket 478 and then another socket with a high number. I feared that it would become soon impossible to replace RAM, CPU or mainboard separately, which would result in higher charges to my custumers.

This is of course exactly what happened, and since it is good for business as a matter of fact, no retailer would ever complain. So in the later days when I found a defective mainboard, I offered a full set of MB, RAM and CPU, often with VGA as PCI was phasing out and AGP was getting in. If the customer would not buy it, he had the choice between buying a complete new system, or stay without computer.

This is too bad, especially for situations like this. But we all are getting this 'innovations' pushed down our throat.

jlinkels

Yes, its a lot to keep up with. That's why I standardized on AMD. Since I am not running a repair shop, just the IT department of my company, I have the luxury of being able to specify a narrow range. That makes upkeep a snap. But at home, doing freebie repairs, where anything is likely to come in, I lack sufficient parts on hand to quickly swap out parts when its not something I am using.

So tomorrow I will call someone who may have some Intel systems. I have gotten them started using Linux, first with a VM in a repair job, then a native install, and they owe me. If they have a known good P4 that will settle it.