My dimension 5100 was working just fine.
Then, just for the hell of it I opened to tower to check the RAM, (was going to upgrade RAM but didn't need to).

After I closed the tower my machine would NOT come on!
I pressed and Held the Power button in the front but NOTHING.
No sounds, No power, NOTHING.

But after opening the tower back up I did notice when I plugged the machine on the green light on the motherboard came on.

I'm not sure whether I should replace the MOTHERBOARD , or the POWERSUPPLY ,
Or do something else .

Please help

You cant replace the motyherboard on dells. They are nonstandard.

Take out the ram and put it back in . Make sure it is in properley.
Secondly, unplug the PC from the wall and leave it for half an hour. Hold the power button for a while while it is unplugged.

Then try starting it up again.

You did protect yourself from static discharge before opening the case, right?

I thought SO . Would you know WHY I can't replace those motherboards?

I'll try taking the RAM out. Not too sure that would do anything but I will try that.

Do you think static discharge could have done this?

The case and motherboard are nonstandard, because they dont use standard front panel connectors. Normally they are just wires with pin headers, but the dells use a small circuit board which provides the power switch, hd activity light, and diagnostic functions. This is very uncommon and connects to the motherboard via a strange IDE-type ribbon cable.

Ive got a 5150 (e510) and my dad has an e520

The PSU in my 5150 is replacable with a standard one, but a new one will be a very tight fit + not very secure.

Yes, static could have done it. And i reccomend taking the ram out because my dads E520 has a similar issue. It would not stop beeping because the ram wasnt seated properley.

Thanks for your fast replies.
I'll take all the RAM out later.

Since static could be the culprit. Do you think the "RAM fix" would still help?
Hopefully I don't have to buy another desktop.

That smile should have been a BIG CHEEESE!

If it waqs static, the machine is probably dead

didnt you wear a wrist strap?

actually NO
I didn't think wearing one would make a difference.
Will any wrist strap do?
Or should it be a certain kind?

This really does suck.
I'm glad I have another desktop

one of those antistatic wriststraps which you clamp to a ground. a good idea to wear one when working on pcs.

i have been working on computers for 9 yrs now ,i don't own a wrist strap and have never fried a stick of ram or a motherboard by not wearing one .unplug power source ,hold down power button and , as long as you ground yourself to the metal case first ,by just simply grabbing the side of the case you should be alright.
=
when you opened the box to check the ram did you take it out ,if yest take it out again and replace it like jbennet said ,also check to make sure you didn't knock any wires /cables loose,especially the front panel connection