OK, the no POST beeps indicates CPU failure (almost %100 of the time). That could have been caused by a wide variety of things. BUT, since you indicate you exchanged both MOBO and the CPU for new, identical items, and got the same result again, then I am looking right at the PSU (power supply unit). Honestly, 250W isn't all that good anymore. Also, if it was a bargain or a light-weight PSU, then I would definitely NOT use that. AMD's tend to be somewhat finicky about power. THere are two sockets for the Sempron 2800+, Socket A & Socket 754. I am assuming you are using Socket A.

Now, what mobo is it? That is an important question. Does it have POST Reporter? Will it tell you what is going on if you have speakers plugged in? If it does, take EVERYTHING out. CPU, RAM, everything! just connect power to the board. If it has POST Reporter, make sure your speakers are on and at an audible level. Power up the board. The Reporter will say "CPU Failure or NO CPU Detected"

That will solve your working/non working Mobo problem. I think you should get a better PSU. I've done a lot of damage to AMD boards by using inneficient PSU's. (look for my previous posts in these forums. lol)
Good luck, let me know

Danyael

Thanks again for the continued help...

I am using the AMD 2800+ Socket 754, not the Socket A.

The mobo is an ECS EliteGroup 755-A2. I'm not sure if it has a POST reporter. This is the link to the mobo description:

http://www.ecs.com.tw/ECSWeb/Product...uID=16&LanID=9

I will try a new PSU. I'll upgrade to a 350W which should be enough. Any other suggestions would be great.

When I clear CMOS by moving the jumper, nothing is supposed to happen because it's now shorted, right? I just push the power button, unplug the computer, and change the jumper back.

Also, for the speaker, there are 4 slots for pins on the plug, yet only two have connectors in them, the VCC and signal slots. Which ones of these should I connect to +? I've done it both ways just incase.

Thanks again for the help!

You should upgrade way past a 350W PSU. Im thinking at least, bare minimum a 420W PSU. Reason? 1. You cpu is a beast.. not literally, but AMD's require a lot of power.. usually more than their specifications. 2. Your PCI video card isnt going to last long in that box. You need an AGP card. even a 32MB Radeon. Get it out of that PCI slot!!!

When you clear your CMOS, once you've switched pins and shorted it out, keep it there for about 10 seconds. yes, just putting it there and taking it off will do the job, but you want to ensure ALL discharge is outta there. So keep it there for 10 seconds, then move it back. You DO NOT have to press power, or anything else.

Now, your speaker. It looks like your board should have (3) pins for your speaker. I believe it will be on the RIGHT side of the pin array (looking at it from the top). And when connect the speaker, make sure the side with the open spaces (the other side should say Speaker on it) is pointing toward the front of the case.
The bottom is Pin headers are the same way. The label side up. incase you were unsure or didnt know.

Now, disconnect everything from the board but the power. *NOTE* Since you have a 250W PSU, do you HAVE a 4pin power connector? Should be a long square design? It will plug in to the right and down from the RAM.. If you dont have one on your current PSU, you will most assuredly need a new one.. immediately. Or you'll do more damage.

Let me know.

Danyael

Danyael's post got me thinking. The old 250 W PSU will not have the 4 pin, 12 v CPU connector. I'll bet that's the source of the problem. I suggest you get a minimum 420 W PSU from Antec or iBall. these are compatible...

Thanks for your detailed help.

My PSU only has the rectangle ATX plug that plugs in by the IDE slots, not the smaller square 12V ATX. I'll pick up a new PSU on the way home from work tonight.

When plugging in my LED to Panel 1, the RST_SW has the - on pin 5 according to the manual, so I have that one facing the other direction. On the plugs there is a small triangle on one of the connectors, which is postive, correct? So I lined that one up with what the manual says is positive (pg 12). The rest face the way you describe.

I'll try and pick up a new video card too.

I'll let you know if the new PSU does the trick. Thanks again for your help.

THE PROBLEM HAS BEEN SOLVED!!!

I purchased a 500W PSU and installed it, using both the ATX and the ATX 12V cables. That did the trick. It booted right up no problem. I was under the impression that the small square 12V ATX was for Pentium 4 processors only, guess not.

Thank you all for your help!!!

Not a problem at all. Glad to hear the problem's solved...

Hello all,

I just wanted to thank the originator of this thread.

I had the same problem building a new computer with an Intel Pentium 4 HT...

I've built numerous computers in the past, but none in the last 2 years. I was wondering what the heck I was doing wrong. As had he, I used parts (drives) from my previous computer, recieved no POST beeps, and was trying to use my old case with a 250w power supply, and looked everywhere for a solution. I had a feeling when the drives wouldn't work after being plugged into the motherboard that I was low on power. It seems to be the case, and I will try that tomorrow and post my results as well in case anybody has doubts about this solution.

Again, thanks to the originator and ALL WHO REPLIED.

Dustin

It worked!!!

I had a dell 5150 with a pentium 4 ht and a measely 300w PSU. I plugged an IDE disk (ibm deathstar) and it exhibited the same behaviour. It works fine with SATA disks though? I think some PSU's just dont give enough juice to the molexes.