Poor SSD performance on PERC 6/.i

Gentlemen?,

I recently bought a Precision T5500 that arrived with a PERC 6/i controller and 146GB 15K SAS drive.  The SAS drive performed very well for a mech'l drive- on Passmark Performance Test scoring 1208 on the composite disk benchmark. 

This was impressive enough that I decided to give SAS a whirl-literally- and bought a Dell 300GB 15K SAS drive.  The idea was to add a spare Samsung 840 250GB SSD as OS /applications drive and the data files would run on the 300GB SAS. and later add a RAID 1 of those.

However, when I added the 840 SSD on HDD0, the Passmark disk score for the Samsung was only 1128- lower than the SAS drive.  The 840 had scored 2600+ in it's former use on a desktop SATA III controller. 

I updated the firmware and driver for the PERC, verified AHCI, and whatever I could,  but can't see the problem so far.  I've read several comments of poor SSD performance on the 6/i but without explanation for it. On Passmark baselines there are a couple of T5500's with high disk scores- 6871 and 3469 and six T7500 systems above 3000. The single T3500 with a 6/i= 4820.  The fastest single mech'l drives on Passmark - which are 15K SAS- will score about 1400. I assume the top scores- over 5000- are probably a RAID 0 of SSD's and the second tier a fast single SSD.

With the poor score on the 6/i,  I tried the Samsung 840 on the SATA 2 channel 0 and it scored 2532- double the PERC score and closer to it's former rating on SATA III.

What am I missing?  If the SSD performance issue is not solved, I'll reluctantly need to remove the 6/i- which might be migrate to a Precision 390. Any ideas gratefully received.

Thanks!

PoultryLogistics

Dell Precision T5500: Xeon X5680 (6-core @ 3.33 / 3.6) , 24GB DDR3 1333 ECC reg'd, Quadro 4000, PERC 6/i with Samsung 840 250GB , Seagate Cheetah 15K SAS, Windows 7 Prof 64-bit