Oh - I thought the problem you were having was it was making the ticking noise.
Same here! That's not normal, IMO.
If there was a hard drive or fan somewhere that had already been excluded, my next guess would be that the power supply is "crowbarring" (clamping voltage output to limit current when its output is too high OR overloaded).
It would do this if something under the PC board is shorting a power rail to the case; could be a board standoff missing, a misplaced or a loose screw, nut, etc. slipped under the PC board and
shorted metal case to a PC board power rail.
I've also heard a failing filter capacitor click on a switching-type power supply such as this; don't recall ever hearing any linear power supplies click.