Compatibility problems with Apple RAID and Samsung Spinpoint F1 ?

During the weekend, we completed testing of the RAID card on a new Apple Mac Pro. Hoping to get the best possible results, we used Samsung Spinpoint F1 1TB disks, which have the best transfer rates today.
Against all odds, and for reasons that we have not yet identified, we encountered problems with speed.
In RAID 0, 4 discs, involving transfers of less than 30 MB, we obtained data rates of reading and writing over 320 Mb/s. But above 30 MB files, write speed collapsed and peaked at 100 Mb/s.
On the same test, conducted without the RAID card, the transfer speed is much higher, close to 600 Mb/s in both directions with files of less than 20 and up to 500 MB.
It is possible that these discs pose a compatibility problem with this card. We will check in the coming weeks.
If you have installed a RAID card in your machine, please keep us informed of the results you have achieved.