problem started when surfing the net and the screen goes black like the video card went bad, had been doing this when using alot of video. bought new MB and Vid card. same problem on first boot. second computer has same problem. tested CPU at work and it is fine. swapped working hard drive from known good computer and still not working. I get no beep codes except on one computer when I take the memory out. once put back in... nothing. monitor works good on another computer. tried a brand new 600W power supply and no luck. I removed all un-essential hardware from both PC's... nothing. the memory on both computers are brand new. basically, when both computers are turned on, the fans start and the cd drives light up on the outside, if a floppy is in the drive clicks (engages) but nothing is read from the disk and the floppy light never goes out. thats it, I'm stuck with two new computers that don't work. looking for any ideas. thanks in advance.

Benchtest the motherboards. Out of the case on a non-conductive surface connect only powersupply, CPU with heatsink fan, 1 stick of ram plus keyboard, and graphics/monitor. Use onboard graphics if available. plug into powerstrip and use a screwdriver to bridge the power-on pins on the motherboard header to see if it will POST and boot into bios. If that is successful then instal the motherboard in the case and repeat the test. If ok then connect one extra device at a time and test after each new device is connected. If you cannot get display in benchtest configuration then you have narrowed the problem to either the powersupply, motherboard, CPU, ram or graphics. I used to have a signature but it disappeared and I just couldn't be bothered writing another so please feel free to ingore this.