Those voltage rails you want are read by the DS1780 ON THE GRAPHICS CARD, I've confirmed this on IrixNet via my fuel rebuild. Without a graphics card installed your L1 will be missing ALL XIO voltages. So what plugs INTO the XIO port is what measures it. The smaller port of the two on the XIO provides the voltages.
Also if you have a burnt out DS1780 on your graphics card (which HAPPENS, it seems to be directly related to a short on the XIO rails, for me it was 12V XIO bias, but I never found out which component was shorted as it stopped when I did a 1.5W 1V injection to look for it , I've not returned to the card yet).