This happened last Sunday when I decided to do an upgrade. What I did: I yanked a bad CD-ROM drive and replaced it with a CD-RW drive (Philips), yanked a bad Eagle TR-3 tape drive, soldered a broken wire to the internal speaker (with the power off), and blew the dust out with compressed air. After that, the system was dead. No signal to the monitor, no beeps, nothing. There was power to the mother board (I checked all the connectors, -5, +12, -12), the hard drives spin up, and I can hear the heads move. I tried everything, including putting everything back to the way it was, removing boards, reseating ram and the processor, pulling off IDE connectors, etc. No luck. No POST. This is a fairly generic tower PC, and the mother board is (was) an S1571S Titan Turbo AT-2.
I concluded (perhaps falsely) that the mother board was bad, so I ordered
a new one. The old one was about 4 years old with a Cyrix 133MZ cpu. So I ordered an ACORP 5AL161 with an AMD 450MZ cpu, and 64 MB of ram. I installed this tonight, made sure all the jumpers were correct, and I have the exact same problem! Nothing! Drives spin up, but that's all. One thing I noticed on both boards is that neither the CD-ROM nor new CD-RW drive will open the door if the IDE cable is connected to the motherboard. If I disconnect it, then both doors will open.
I doubt if my video card died (STB Powergraph 64), since I know the system isn't booting, and there aren't any beeps.
Any suggestions? I'm going nuts!