This is material gathered from newsgroups.
This is in no way a confirmation that any of these will work in your 320.
All i say is that since these cards use the required voltage, they may work.
I hope to test some of them soon. Please mail me if you have to add something.

SCSI adapters

This list is what i got out of an old SGI japanese site which has been discontinued in other languages
(i don't speak japanese :( )
[ link ] ... but if you do...
Adaptec SCSI Card 19160  Ultra160 SCSI
Adaptec SCSI Card 29160N  Ultra160 SCSI [ 29160 family PDF ]
Adaptec SCSI Card 29160  Ultra160 SCSI [  29160 family PDF ]
Adaptec SCSI Card 39160  Ultra160 SCSI [ PDF ]
Adaptec SCSI Card 2930U2 / Ultra2 SCSI
Adaptec SCSI Card 2940UW Pro  Wide Ultra SCSI
Adaptec SCSI Card 3940AUWD  Wide Ultra SCSI
user reports
Adaptec 3950U2W
is working, states christian ["....is working properly with nt4 and w2k although you see a conflict on IRQ1 regarding the
fact, that both channels are listed seperately "]











as i heard from milton , the qlogic 1080 is the only device which is able to boot
from a SCSI disk.
maybe the 1280 too because the 320 was shipped with that one, too...


Video cards (for use with a second monitor under 2000)

ELSA ERAZOR II PCI
ELSA Synergy II PCI ***might work
ELSA GLoria Synergy PCI
Voodoo 3000 PCI
 Diamond FireGL1000Pro PCI 
Appian Jeronimo Pro Dual Head PCI (using this card, a 3-monitor setup should be possible) 
According to Bart De Lathouwer , the Diamond and Appian cards are conformed to work.


Other devices
Mpeg1 encoder & AVI capture card BROADWAY 2.5 STANDARD
[site ]

I've heard the Turtle Beach PCI Sound Card works on the 320.