Seagate 3TB fine in one mobo, not detected in another

[ssalim]

Seagate barracuda 3TB. Split into two partitions: 2TB and 0.8TB (approx). GPT.
It works fine in one mobo (newer) but not in another. I see it in BIOS as junk character (instead of the hdd model# or whatever)

Works in: foxconn h61s + intel pentium g860
Does not work in: intel atom d510mo
(used to work until the hdd had issues so I messed around with it)

Both are running win7 64bit.

Any ideas?

Thanks.

 

[popatim]

one motherbd is 3tb capable and the other is not.

 

[ssalim]

The intel atom d510 is not? But it used to.
Maybe it does not support GPT? (maybe it was MBR before I fiddled with it)