Dead Hard Drive controller?

Hi there,

I have an iMac that one day booted up to the folder/question mark screen. I decided to try disk warrior which couldn't find the hard drive at all. Of course my first instinct was that the HD was dead so I decided to throw in a known good Hd that I had lying around. Turns out that that hd couldn't be found either. I could tell the Hd was getting power so I tried a known good sata data cable. Still nothing. Also I tried to put it in target disk mode but the fans just started blasting and the screen would stay black. I'm assuming that's what happens when there isn't a disk to be targeted.

Other things I tried was starting from a leopard dvd and using disk utility. No disk appears! An external usb drive showed up though after I plugged it in. I proceeded to try to install leopard to the external drive but it failed part way. Also I wasn't able to boot from the original disk after I pulled it from the machine and put it in an enclosure. It would not even show up as a startup disk! I started to suspect the logic board but a ran the ASD utility disc looped for 7 hours and the machine passed!

Could it be that just the connector for the SATA drive on the logic board is faulty? Anyone else had this problem?

Thanks,

Cory