I suggest try installing IMSM 8.8 (yes it works on the P55 chip) and see if thats any better no need to uninstall IMSM 8.9 (which you are likely using) and will install the 8.8 RAID drivers when you install it.
thanks for the tip however raid driver ver 8.8 did not help . The results are as follows
raid driver ver 8.9 single non raid drive = 112 MB/s striped raid read = 115 MB/s ( should be about double )
raid driver ver 8.8 single non raid drive = 95 MB/s striped raid drive = 112 MB/s
will try a 3 way stripe and revert with the results in a day
"Intel" why no software debugging before release ... Need someone to do it for you ! ?
You took the SATA 1.5 Gbps limit jumper out of the drive?
Problem Solved .. Thanks for your responses .. below is the summary
Yes the drives were all unjumpered for SATA 3.0 and the interface speed verified with "hwinfo"
The configuration was 2 Nos 500 GB HDD Striped ( Seagate ST3500641NS NL35.2 .. these are NearLine SATA drives )
It was not the WD Raid Edition Drive (YS Series ) as reported earlier
When replaced with the regular Seagate 7200.12 the performance jumped ( doubled )
So it is clearly a problem with the Seagate NL Series drives