Ah! I was wondering if this was in some way related to the
apparently-undocumented 'iKVM' feature (comes with really annoying
ungoogleable name identical save for case to that of major Java package).
Apparently it is.
(I'll see if it's documented in the motherboard manual when the machine
arrives tomorrow, after one motherboard failure and one evaporation in
courier transit. Someone Up There does *not* want me to have this