|"assumed the drive was dead,and so I bought a new one. It doest work either, whatever connections I make - tried switching both cable."|
Sometimes a power supply DOES fry the board on an optical drive while failing (it's even more common for that to happen to floppy drives), but the new DVD drive should work, if the power supply didn't damage anything else while failing (e.g. the data cable to the drive) , and if the cable connections to it are correct and not damaged by something you did, and if it's an IDE drive, the jumper setting on the back of it is set correctly.
ATX mboards are always powered in some places by the ATX power supply, even when the computer is NOT running, as long as the PS is plugged into the mboard, the PS is switched on if it has a switch, and the PS is receiving live AC power.
Did you unplug the computer, or otherwise switch off the AC power to the computer, at ALL times, when you were fiddling with connections inside the case ??
If no, you may have fried the drive by merely plugging in it's power connection.
If yes, what do you mean by "It doest work either" ?
Did you remember to plug in it's power connector?
Even if there is something wrong with the data cable connection (unless something is shorted on it) , even if the data cable is not connected, if the power connector is plugged into the DVD drive, while the computer and Windows is running,
- the drive's tray should eject and retract when you press the button for that on the front of the drive,
- the drive's led should come on when you press that button
- and the drive's led should come on for a short time when you insert a disk in the tray and retract the tray.
Regarding the data cable connection, and the jumper setting on the drive if it's IDE, see Response 8 in this:
and - did you examine the data cable connection on both ends for evidence of damage - e.g. scorch marks, carbon deposits, etc. ?
Rarely, a power supply can damage something else on the mboard while failing - possibly the circuits for a data cable connection. Try it connected to a different data cable connector on the mboard.
Try the drive connected to another mboard.