Hello, Anyone got any ideas to whats going on? I'm stumped. 2008 8-core 2.8ghz Mac Pro The 2 old drives died ages ago and I have only just got round to replacing them. The system seems to run fine with nothing in the optical bays. When I connect a optical drive to the molex+sata (or pata) in the optical bay the Mac won't boot. And the OT (over temperature) LEDs light up on the logic board (Also the RAM LEDs all lit up simultaneously a couple of times but seem to have stopped). Shortly followed by the smell of burning plastic from the DVD drive. Thinking that the PSU must be on the blink I opened it to check for damage on the power rail effected. All seemed fine (no popped capacitors etc). Bought a new PSU, arrived yesterday. Doesn't exactly the same. Any ideas? Thanks.