I really wanted Irix 6.5 on the box, and it was running Irix 5.x. When I restored my SGI Indy, I ended up using my Sun CDROM drive, and it worked perfectly. All the workstation CDROM drives back in the day used 512-byte sectors. Most newer CDROM drives use much larger sector sizes and, as a result, don’t work well with period workstations. Some devices, specifically used in early SCSI macs often have a sector-size jumper that you can set and they too will work with Workstations of this era.
When I acquired my SGI Indy, it came with a complete set of 6.5 OS CDs. This was extremely fortunate because I'm not sure how I would have done the install with just CD images on the SCSI2CD. A full Irix 6.5 install is like 10 CDs, and you shuffle them in and out a lot. Fortunately, the install went without a hitch, and in no time (well a day), it was up and running on my network.