|Did you vacuum the outside, or, worse, the inside of the computer case ?|
Vacuums (that were not designed to be used with electronic boards) produce a tremendous amount of static electricity when running, and anything connected to them can discharge that to your components.
The lower the humidity in the room, the more likely more static electricity will be produced.
If the carpet has synthetic fibres (cotton dissipates static electricity naturally) it's likely more static electricity was produced.
You may have damaged the power supply's circuits, or in any case, failing power supplies are COMMON.
They often partially work, fans and hard drives may spin, leds may come on, yet you may get no video and the mboard will not boot all the way.
See response 4 in this:
The only way of ruling out your power supply as the cause of your problem for SURE is to try a known good power supply with your system, that has the same wattage capacity or higher. .
If you can borrow a power supply from another working computer, try connecting that.
Also, if you DID vacuum inside the case, you may have knocked something loose.
Check all the connections of the wiring to make sure they are all the way onto their pins and into their sockets, especially the main connector from the power supply. The wires close to the mboard going into the main power connector/socket should be more or less perpendicular to the mboard surface rather than at an angle.
Make sure the ram and all cards in slots are all the way down in their slots.