Lets hope someone can help !

We have a PE1800 with 4 x 73GB SCSI disks in RAID 5 config. Returned after xmas to find server beeping. Checked OM and it reported disk 0:1 had failed. Inserted replacement disk in slot, system did not rebuild just continued beeping. Anyway after a lot of testing we are pretty convinced the disks are not at fault. We think this because we temp replaced the 4 disks with 2 x 73gb disks and setup in raid 1 config and left server running overnight. In morning returned to find server beeping and 1 disk again reported as failed. This just cannot be right.

We have now replaced the Raid controller card with same but on board bios A00, the original card was A03, system bios A05, rebooted server but now fails to detect new Raid controller card during POST, everything else the same. Put the original Raid card back in and card is detected fine.

Any solutions or ideas, we are just about out of them ?