Poor RAID-5 performance with 3Ware card??

I just installed a 3Ware 9690SA 4-port RAID card with the following hardware:

P6T mobo
(3) RE3 1TB drives
RAID 5

Also, firmware is at the latest level.

The initialization process finished, and I promptly ran a quick benchmark with HDTune. Basically, the results were less than I was hoping:

Transfer Rates:
Min: 69.6 MB/sec
Max: 108.3 MB/sec
Avg: 94.3 MB/sec

Access Time: 10.2ms
Burst Rate: 92.2 MB/sec
CPU Usage: 1.5%


Is this typical of 3-drive RAID5 setups? If not, any suggestions for improvement?

Thanks!

Did you plug in a BBU(Battery Backup Unit)? Without it you can't use write-back caching which is essential for RAID5 performance. Instead the controller will use write-through and does not take advantage of the onboard RAM.

[EDITED]Unless there's an option in the controller's BIOS (e.g. pressing Ctrl+R during POST) or in the 3Ware management software that can force write-back on without the presence of a BBU. Not recommended unless you have an UPS.

Does anyone here know which pci-x (64/66) IDE raid controller I should be looking at for Raid 5 (3+1 500GB drives) and workstation/light server use? Someone told me the 3ware 7506-8 is a good choice but judging from the 8506-8 benchmarks, I think there must be better.