The system has been running in this configuration for nearly a year up untill this week when I logged into windows the Nvidia nvraidservice.exe would start crashing then I noticed boot times had increased. So I benchmarked HDD performance with Sandra soft 2005 and found my disk performace had over halved its original speed of 194MB/s to 95MB/s which is slower than a single Seagate 200gb sata2 drive I also have in my system.
I have tried repairing windows to no avail so I started from scratch deleting raid set and re creating stripped array and clean installing OS but still no luck I am at a loss to explain cause unless it was a BIOS upgrade or some other driver related issue.
This Is orig benchmark from original build install:











