Right now I cant get to the machine (off, in the basement) but it is some run-of-the-mill SATA drives using a SATA expansion card.

It works great but I just use it for /opt since I ran out time to move more of the machine into it.

You cant boot off the SSD, so I still use a SCSI but you can replace that too if you boot the SGI off the network.

Silent SGI:

Having gotten rid of the SCSI drives completely w/ the network boot, you can put a modern, more silent, PSU [1] (but hurry, ones w/ enough current on 5V (?) are rare), and then replace the GPU and CPU fans and turn of environmental monitoring.

[1] i had to replace mine; my 500 MHz Fuel is notorious for bad psu

Do not turn off environmental monitoring. That's for debugging only. That's how people are cooking the video cards. Please get your fuel /properly/ repaired by say weblacky on irixnet. The reason why? With env monitoring off, the system won't respond to overheating on the graphics card and it'll cook it alive. The fuel has notoriously bad airflow (air doesn't move right angles)

You could use the NVME driver to load the filesystem and boot the kernel diskless...