Scenario: I have a dell (never will make that mistake again) dimension 8100. I've had it for about 3.5 years and usually keep it on straight for a few days. It was on one night and when I got up in the morning it was off with the power light blinking, I could hear a fan only. The power supply fan was on and so was another tower fan, but thats it. I tried another power supply but nothing, could this be the motherboard, even though the light on the motherboard was on? Plz help, thanks in advance!

Hi

Did you use a Dell power supply to repace the old one?

Dont think its you PS, reboot and see if you get error beeps, if not, remove all cards, and reboot to see if you get error beeps, if not remove the ram, reboot and see if you get error beeps.

In this case you actualy wanting beeps, if the computer beeps No Video, when the cards are removed, or Bad Ram/Checksum Error with no RAM, then atleast you know the mobo is working since its attempting to run POST checks.

Post back with more info.

If you didn't replace the PS with DELL power supply, you probably killed the motherboard (if it wasn't already dead). Dell wires their motherboard differently than the standard.

Sorry Pete, that's not true.
You can use a standard power supply as a replacement.
Dell mboards are not made by Dell - they are made by mboard manufacturers and OEM'd to Dell, who slap their own bios on them, often exactly the same as the mboard makers with a Dell logo displayed on bootup, bios string often only a tiny bit different.
Their is nothing proprietary about the mboard.

Rami did say "The power supply fan was on and so was another tower fan, but thats it. "
He doesn't mention the cpu fan - if that was dead, the cpu is fried.

Assuming this isn't a case of the cpu overheating to death (cpu fan stopped or spinning too slow, etc.), and/or he hasn't gotten a damaging power spike or surge during that night and has no protection from that, what I suspect happened is the original power supply failed in some of its circuits. What damage that does, if any, varies at random, depending on what it did before those circuits failed. If you are lucky, there is no damage, and replacing the power supply restores everything to normal. If you are not lucky, often because the power supply shorted something, it could have damaged the motherboard, and/or the cpu, and/or any of your drives, and/or any of your cards.

Rami should try the cpu in another mboard to rule that out - that may mean a trip to a used computer seller. He could also take his case with him, and try another cpu in his mboard.
He should also look inside the old power supply to see if there is any obvious damage - burnt components, blown fuse, bits of a blown up capacitor, etc. If he can't see anything, he could also try out the old power supply on another mboard.

Hi

Well the first thing I wanted to know is what PSU was used to replace the old. I ask for a very particular reason.

I don't know how far back Dell deployed one "Baffle Engineering" tactic - to rewire the standard ATX plug.

Maybe all those who write about the stupid rewiring into a standard plug are mistaken. Hmmmmm maybe moon landing fake too. It would have far wiser to use a modified plug, but that was the whole idea - to burn customers who are confident to work in the little box of tricks themselves.

At some point Dell would have use standard PSU connection, but its reported they don't anymore. Perhaps Dell have changed back?

Hi

Actually I learned/confirmed something a few minutes ago. I gather Dell machines in the last couple of years have standard supplies.

[yeah so Mike is very correct]

As it is a P4, what Mike said is true. So my apologies to Mike, for my remarks in previos post. Also thanks, I haven't worked on any Dell P4s yet, and that nipped one of the little quirks which would have see me arrange for a replacement Dell power supply, if required.

Update:

it has taken me a while to get around to trouble shooting but here are the results. The power supply that I tried was from another dell computer of the same model as mine and it still didnt work. As for listening to beeps...dells, or at least my model, dont beep they instead have 4 small lights in the back of the tower (part of the motherboard) that light up. I took all pci slots out including ram and no lights lit. I thought it was the motherboard so i replaced that (a dell oem part) and STILL NOTHING. What could it be, its driving me nuts. Thnx!

I have a dell 8100. When I have a powerfailure in the house or the powercable is disconnected, I can't start windows. This applies both when the computer is on and when it is off (when the powerfailure happens). The solution to my problem is to enter the bios and change the clock date and time, as this has been reset due to the sudden powerfailure. Don't know if this is the case for you but worth checkin out.

Regards,
Jorgen
PS. If I understand you correctly...you can use a standard PSU with this system ? as I really would like to upgrade my PSU to i.e. 300w to add a Geforce Fx5900 card...

I had a similar problem once. I had to set a special jumber on the MOBO to reset the CMOS. (i think that's what i reset...) Anyhow, i had to leave the jumper in place for like 10 minutes, then i put the jumper back where it usually is, clicked the power button, and everything was fine. Try it out!