I was given a never-used Seagate Barracuda 7200.12 1TB (out of warranty) that the user couldn't get working but never bothered to RMA. But my PC won't even turn on when the harddrive is plugged in, I just get the green case power light on, but no bios beeps, no fans spinning, nothing. And the power light doesn't turn off until I disconnect the PC power supply and the motherboard's capacitors discharge after a few seconds.
This only happens when the SATA power cable is plugged in to the aforementioned harddrive. My computer will at least turn boot when that cable is disconnected, but of course it won't use the HD because its power cable isn't plugged in. The PC will boot fine if any other hard drive is plugged into the same connectors, so it is not a power supply or connector/cable issue.
I took off the rear circuit board (without opening the HD and exposing the discs to dust) to check for obvious bad or disconnected solder joints, but they all looked fine. Using some steel wool I shined up the 3 gold connectors that press on the 3 prongs coming out of the HD enclosure, but it didn't make a difference.
Does anyone here have experience with advanced HD repair, or this harddrive, or this problem, and might be able to shed some light on it?