I have a P55 FTW, this boards has run perfect for me since i got it in 2010. However i am trying to run a raid 10 setup. it installed fine but harddrive 4 which is on sata port 3 keeps failing on me. i have tried known good working harddrives in this port and it locks up my PC as soon as it starts to rebuild. I have never used this port till now. I have run a RAID0 setup till now with 3 harddrives.  Even if i stick a harddrive in the port my PC is hanging at the windows logo or bluescreens.  If i remove a drive from that port i have no issues. I'm guessing the port is bad??
 
My specs are: 
 
CPU: i7 860
Motherboard: EVGA P55 FTW
Harddrive: 4 x 1TB Seagate 7200.12 drives with 3 spares
GPU: 2 x AMD 4870 in crossfire
PSU: Corsair 850W Pro