Very Strange: SCSI performance

[SCSI]

I am getting surprisingly low SCSI scores:
System
Intel Quad Core Extreme Edition Core 2 Qx9650 3 GHz
8GB DDR2
15K RPM Hitachi 73G LVD Ultra320 SCSI drives
Hardware RAID 1 (Adaptec)
Windows 2008 Server Enterprise Edition x64

The SCSI disk tests show:
37.7 Seq read
42.1 Seq Write
9.1 Random R/W

Now compare these scores with those for the the lowly Seagate SATA II drive in the same system:
120.8 Seq read
95.3 Seq Write
3.4 Random R/W

Any ideas? (I have tried replacing the MB, backplane, cable, drives, with more or less the same results.)

PS: The 64 bit Performance test installed ok, but would not run on this system. So these tests are with the 32 bit software (a licensed version).

Thanks for your help!

[David (PassMark)]

...but would not run on this system

Can you give more details. Was there an error message of some sort? What version of PerformanceTest are you using?

Are the drives connected via the motherboard or via an external card. Out last attempt with mirrored drives (with a hardware controller) gave awful results.

Have you checked you have the latest device drivers for the RAID controller?

If possible can you check the drive in a non RAID configuration?

You might also want to play around with the Advanced disk test in PerformanceTest to see if any scenarios give better results.