Hi Hellfire!
I don't know if I can help, but I'll try to give you some ideas...
First of all, have you tried to test the drive with another SATAIII cable? If you don't have one, you can use the cable of the 1st drive.
You could also switch the two cables, and if you see that the 1st drive (with the cable of the 2nd drive) is recognized as SATAII, then it's the cable's problem. If it's still recognized as SATAIII, then we can be sure that the cable has no problem at all.
Another thing you can try, is connecting the drive to the Marvell SATA ports.
If the drive operates at SATAIII standards, then I guess there might be a problem with your onboard storage controller.
Hope it helps.