A squeaking SMPSU normally means it's detecting an error (overcurrent, which may, in turn be due to overvoltage tripping a crowbar circuit which then shorts out the suppyl), shutting down (the oscillation frequency may then go trhough the audible rangs), then starting up and trying again, etc. If the problem is certainly inside the supply (i.e. it contines doing it on summy load), I'd suspect either a failure of the regulation feedback loop (thus casuing the overvoltage problem), or a shorted capacitor or rectifier diode on the scondary side of the supply. -tony