Chosen Solution
Installed a new Toshiba 500 GB HD from ifixit. It shows up as a 1 TB HD and will not allow me to erase or partition it from the original start up disc, nor tiger, nor snow leopard. Says input/output error. I’m a noob-trying to save this thing. I replaced the HD 4 years ago with no problems. Did I get a bad HD or is it something else? Any help is appreciated.
The hard drive is probably rated to fast for your machine. It needs to be jumpered down to 1.5 Gb/s to operate properly on your machine. These jumpers are located right next to the power and data ports.
