SCSI speed for SGI O2 and additional controller

[Giuseppe Sacco <giuseppe@eppesuigoccas.homedns.org>]

Hi all,
I am just starting using this O2 and I found the disk access is *very* 
slow. The internal controllers seems to be adaptec AIC7880 and the speed 
for each device is 3.3 MB/s as shown in /proc/scsi/aic7xxx/0:
Target 1 Negotiation Settings
       User: 3.300MB/s transfers
       Goal: 3.300MB/s transfers
       Curr: 3.300MB/s transfers

Do you know if this is the maximum speed for this controller? I have a 
spare SCSI PCI card from Advansys, may I plug it into the SGI and use it 
for all my harddisks? Should I leave one disk in the internal controller 
in order to boot?

Thanks,
Giuseppe