[jan-jaap]

Did you measure the actual voltage it complains about?

I'm facing a similar problem in my Challenge L deskside which was complaining about the -5 and -12 being out of spec. I measured them and they were fine, it was the monitoring circuit that was broken. Borrowed the system controller from my Onyx IR and all was good, installed a spare system controller and (1) that one complained that all voltages were 10% too low, but (2) the 5V supply which feeds the MCU on the system controller (which has 8 A/D channels used for measuring voltages and the blower) was 10% too high @ 5V6.

I'm now waiting for parts to rebuild the 5V supply on this system controller.