Ok, thank you very much CV880. That makes a lot of sense, I suspected something like that was the case, but don't have a way to confirm it.
On a related note, I have read on the 777 that the cockpit flight displays are normally DC powered. I suppose this simplifies standby power scenarios by eliminating the need for a standby inverter? On the 744/748 the displays are AC powered (standby or transfer buses).
Do the individual displays in the 744/748 have inverters built into them (like a household LCD TV would) that take the 115V 400hz AC and convert it to DC that's useable by the internal components of the LCD unit? Maybe there is a technical reason for this change on the 777, given that the 747-400 originally came with CRT displays (maybe it was easier in the 80's to use CRT displays with AC power, even though, as I understand it, CRT's internally convert AC to DC anyway). Maybe there is some minor weight savings and elimination of complexity by supplying the displays in the 777 directly with DC power?