Well my HDD problems are back..

This time it started with the disk connected to sata-port 2. When I later unplugged it the disk in port 3 started giving me the same errors -_-

I'm thinking it's the mobo, it feels like I've tried everything now, formatting both drives, updating bios etc.

Guess the only thing left to do is to try the disks in a friends computer before returning the mobo.