I am quite frustrated, since my clean install of Windows 7 Ultimate 64 bit, the raid 0+1 (AKA Raid 10) keeps crashing on the 4th drive and I have even replaced it with a brand new drive to see if it would correct the problem. At one point a couple weeks ago the third drive crashed too, but that was just a one time occurance, I rebuilt the array and it has been fine since. When I replaced the 4th drive on Saturday, it has been fine until this morning. I am running an EVGA X58 with the Intel onboard Raid Controller. I have 4 Western Digital 500GB drives operating in the Raid, 3 are 16mb cache and the 4th is a replacement and all they had was the 32mb cache. WD's website indicates they are recognized as identical other than this. Any thoughts or do you need more information before you could suggest anything?