Crazy motherboard problems

[Thyme]

My friend bought an ECS K7S5A motherboard and AthlonXP 1600+ from newegg. He comes over here and we replace the motherboard on his old system with it. I had just installed the motherboard on a computer for my father and had no problems. But we hook everything up and when we go to turn it on, it gives 8 beeps. We look online for documentation and find conflicting reports, mainly people saying that means a video error. So we reseat the video card, swap the video card, swap CPUs, take out every IDE, Power, sound, everything from the front of the motherboard and plug in only the video and power. We still get the beeps. No matter what we did, we still got the beeps. Having tried with all the hardware I could, I assumed it was DOA. We RMAed it and got a new one. So we put it in. Without anything in but the CPU, RAM, Video, Speaker, and power switch, we plug it in. We turn it on and we get the same beeps. We turn it off and then on and it POSTs fine, just beeping because of keyboard and memory changes, etc. We then put everything in and then it got the beeps, always, but now it also was beeping 2, a pause, and then another, signifiying system memory errors. So we take out some things and it works. We start putting things in and it works. We attributed the cause to the floppy disk because without it it works fine. So we install windows and drivers and all that jazz and then he goes home. He tries to turn it on, and he gets the beeps. He's tried taking everything out and swapping everything and he can't get it to POST, either. We're all clueless. The only thing I can think of as maybe a possibility is it being the power supply. It's kinda old, but it's 250W and should be enough, and it does get power so I don'tt hink it's just being underwatted, especially with none of the drives and such even connected. With everything unplugged, the only difference between his computer here and at his house is the incoming power, and he's just a few blocks away so I can't really attribute it to that. Any ideas? We're really in the dark here.

 

[Thyme]

OK so he picked it up and moved it to another outlet on another wall in the same room, and it POSTed. He brought it back and it worked. He had to reset to install and update (damn windows) and now it won't POST. We're almost positive (no pun intended) that it's the power supply being crappy and being picky.