VIA 6421 pci card and Maxtor 250gig trouble

[ElectroBlaster]

Im having serious issues with a maxtor 250gig sata drive that was originally on an on-board sata port. I moved it to a pc where both sata ports are used up and it has a via 6421a pci card fitted. the drive works ok but its smart report thing is telling me about ata crc errors, they vary wildy but this problem wasnt present using an on-board sata port.
Speedfan says I should get the data off this drive quick because it could fail, I just dont understand whats going on, Ive tried 3 different sata cables and tried powering the drive using either a molex or a sata power lead.
I also have another one of these via sata cards in another pc with two seagate barracudas and they are (touch wood) fine.

Im stumped, it seems like ive damaged this drive just by moving it

 

[rpstewart]

Have you tried swapping the drive with one of the ones on the onboard controller? It may be that the VIA card is dodgy.

 

[ElectroBlaster]

The on-board satas ok, I havent put that 250gig on the onboard as yet because im fed up with it all but I will try it out and see what happens.
Ive been reading all sorts of different things via google ranging from dodgy sata cables to a bad psu. I dont believe the sata cables are at fault and the psu works because the pc is solid as a rock.

This problem has only appeared since fitting the via card, bad luck seems to hang around me like a nasty smell

EDIT: the via card is dodgy from what i can suss out. all 3 drives work correctly on the motherboard sata's.