Large Drives 1.5TB in Intel based XServe (early 2006)

We have tried to put large 1.5TB drives in an XServe with no luck so far…

1st attempt: 1.5TB Seagate Barracuda Drives (firmware CC1G)
we first tried Raid 1 on the drives and occasionally one of the drives would not mount.
we determined that Raid 1 would not suit our needs so we added the $800 Apple Raid controller card for the XServe.
so once that was installed we RAID 5’d the drives. It looked like this might work but when the server was shutdown and rebooted a drive would not mount randomly and forced a slice rebuild.
We called Apple and of course they said that non-apple drives were not supported with the server and they could not help in that situation. They did offer a hint that it’s possible that the drives were not reporting their SMART status correctly or in the format expected by the XServe Raid controller. O.K., I guess I buy that? We read that there were some timeout and/or firmware issues with the Seagate 1.5TB drives so we replaced them…

2nd Attempt: 2.0TB Western Digital Drives
We installed the WD 2TB drives in each of the 3 bays and this was much worse. Rarely will one of the drives post and if it does post, it takes longer than expected spin-up time (approx. 5-10 minutes).
So, I took out the RAID controller card and replaced it with the original SATA controller and the same thing occurred — 1 of the drives would post if I was lucky.

The machine came with a puny 80GB drive and if I use that drive in any possible configuration it boots up perfectly no matter the bay or controller. The other drives, and no more than 1, may or may not post.

Has anyone had any luck putting 1TB or larger drives in an Intel based XServe (early 2006)? Or, does anyone have any ideas on how to get these drives to work?

The firmware of the XServe is XS11.0080.B03
and the SMC Version is 1.1lf5

Thanks!

–jason