How do the compression connectors look? Warped or oxidized? Any evidence of overheating, charred PC boards in the system unit or power supply? Non-Vpro graphics are pretty cheap these days when they show up on Ebay. Or you could pay the premium price for a brand new one at Ian's depot...
Bit of a hiatus while I took over the study as a computer room, put up some shelves and added a second desk - more elbow room for tinkering, and s second monitor!
Compression connectors looked OK, though I've only photos for comparison never having seen one "live" before.
graphics - after a bit of research on running dual head, I added a "+xinerama" option to the Xservers file and got a two-screen desktop. Unfortunately the LH half shows up on the monitor to the right, but that's just a matter of cabling (or playing with "-hw board= ..." options). So those CCs are OK!
CPUs - PROM hinv now shows two, but IRIX hinv shows one. Need to run the diagnostics again, but maybe it is a software/kernel/config issue? This machine once had a CADduo card in a cardcage, I am sure - there is a "Xservers.2key" file which would have configured the two heads for two kbd/mouse inputs (/dev/input and /dev/input1). Since CADduo was intended for dual-CPU machines, I am wondering if there is some legacy configuration that I need to clean out in the absence of the CADduo card to reinstate normal "single-seat" operation, or perhaps I should create a new kernel file (though that might not help if IRIX can only see one CPU - is there a "force 2-cpus" switch?). This may be a red herring - AIUI CADduo did not dedicate one CPU to each user - so other ideas welcome. Does PROM hinv get system info in a different way and cannot spot that a CPU is "dud"? Does IRIX set a lower fault threshold?