Help! Chirping IIgs PS...

[eddy@cs.ucdavis.edu (arekusu)]

To my horror, this morning when I flipping my GS on it emmited a
rapid chirping noise, power cycling with each chirp. (maybe 8-10
times a second...)

(system description at http://wwwcsif.cs.ucdavis.edu/~eddy/gs.html)

Pulled all cards, plugged just the GS into a different wall outlet,
tried again. Same thing. Reading the Hardware Ref, it mentions the
power supply will exhibit this sort of behavior if it detects a
short, or "no load"... 

any ideas? Common causes/cures?

thanks,
alex