Problem with sata 2 hard disk (transfer stumbling)

Hi everyone,

I have a problem with my hard disk,maybe the answers to my question are already here but i didn't saw anything related to my problem so far,i'm sorry if i'm wrong.

Weeks ago i bought an internal hard disk - Samsung HD103UJ (1 TB),when i tried to create partitions (NTFS) and format it,gave me an "I/O device error".I've restarted the PC,tried same thing and it worked now,no error messages.After doing that,i tried to copy some folders on the new hdd but the transfer was stumbling when he reached 70-80% of the process,i've tried many many times to copy things on it..same result,even tried to download from internet directly into the hard disk but every time gave me the I/O device error.Hours later he worked fine for about 2-3 hours and after that those error messages came again.Then i've limited it with the jumper,i thought my motherboard (P5ND2-SLI) doesn't support sata2,but i saw in bios that he has sata2 support..anyway,no difference,the hard disk was acting the same: transfer stumbling and I/O errors.
I've returned the hdd to manufacturer,received another one,WD1000FYPS (1 TB).He has the same errors like the samsung had.Tried the same to limit it with jumper..nothing.So the problem is from my PC not from the hard disks,but what may be?
I use Windows Vista Ultimate with SP1,i have another 4 hard disks,3 of them are on sata mode (i've tried the two hards above with only the booting hard and gave same errors).Motherboard is P5ND2-SLI,bios is updated to last version.


Waiting for answers,thank you.