Sun x4150/SG-XPCIE8SAS-I-Z Random Failures
This is a weird one. Had some curious issues with a number of x4150 systems and LSI RAID cards. The cards would randomly swap between working or not working, unless placed in the middle expansion slot.
Thankfully, the cables leading to the drive backplane are just barely capable of reaching the middle slot.
Helps to pull them and reroute them - you can get them to fit snugly but not ridiculously tight.