I hope someone can help me....looks like a lot of knowledge on this site but did not see anything in a search on my issue. I am building a computer for my father-in-law and I am having an issue. He received a Celeron 3.2 from his nephew as a gift and needed someone to put it in. I had to order the board and the ram so I ordered it from newegg and ordered a ECS P4M800PRO-M478 board and 2 chips of 256 ram to put in it. He is not doing much other than using the computer for internet access and now hooking it up to his security monitors for his house.....so I wasn't looking to break the bank on board and ram.....100 bucks or less. So anyway I got all the parts and put it together. The case is old.....it had a 500mhz P3 in it so the power switch did not line up and the cutouts in the back did not line up.....so I have to get the dremel out and cut the back of the case open to get everything to line up.....then took the manual for the board and looked up how the power switch was wire (the pin numbers) and put that together. I put everything together as it was before and started it up and no signal to the monitor. My first thought is it is a jumper set wrong somewhere......checked the CMOS jumper as per the manual and that was set correctly. I tried different ram in it.....I checked to make sure the processor was seated correctly.....I tried a video card (the board has one built in)....double checked the wiring and followed the manual up the the point of it going through the bios settings. Still no good. I hope this is not a DOA. Does anyone have advise for me? Right now I have the master drive hooked up.....the processor installed and 2 chips of 256 installed and thats it. There is no speak in the case nor could I find a place to hook a speaker up for any beeps to be heard. Everything fires up and the fans all run and the drives turn but no signal.

What make and model was the computer, or was this a custom build?

My first thought is that if this was a retail computer then there is a possibility that the PSU was may not be ATX form factor. Some companies like Dell are proprietary in these regards, and the pin out of the PSU isn't the same as ATX PSUs.

I just read the motherboard manual, two things of note

ECS recommends a power supply of 300 watts, and a 24 pin ATX that supports ver 2.0

Thanks for the replies guys.....I think you may be on to something there. The computer was a Gateway from way back. I dont know what model it used to be but it was a "performace" series. I cannot seem to find out too much on the components in the case and I have no manual for it......maybe I shoudl just have him bite the bullet and get another power supply?

Right on the money......I just pulled out the power supply and it is 200W. I am going out to buy one now. Hopefully that fixes the issue. I will keep you posted!

Replaced the power supply with a 400W and same thing? I am baffled.

Have you tried unplugging the IDE drives and floppy(if you have one) and just try booting the computer with just the board hooked up. One time I had a bad hard drive that was stopping the computer from booting when it was hooked up. When I unplugged the drive, I was able to get to the BIOS. I put in a different hard drive and it worked great. Just a thought.

In order to get post beeps if there is no internal speaker. Plug your external speakers in the audio port on the motherboard. Since you are able to get into the BIOS your computer seems to be posting ok. The first thing I would try is a different monitor. If the standard resolution on the motherboard graphics is too high for the old monitor it wont display anything. Since the older computer was a P3 the old monitor may be outdated for the newer graphics chip.. After you try a different monitor and get the computer set up. reduce the screen resolution to the minimum and try the old monitor again. If this doesn't work we can trouble shoot further.

Edit: Welcome to BC

I did find the issue....the old power supply did not have the aux power hookup.....I had to hook it up on the new one and worked. I have some new issues now I need to work on.....no sound....doesn't boot back up after restarting.....I will have to get more info though on these issues and post if I need some help. Thanks guys!!

Ahh The 4 pin aux CPU connector, sneaky lil devil