Does this mean imminent failure?

A very small event occurs when I shut down this PC at the end of the day and I'm wondering if this indicates that either the Powersupply or MB are getting ready to say goodby.

At the end of the day when I shutdown the PC, I flip a switch on a powerblock that turns off all power to the PC, monitor, etc. This is of course after Windows has shut down and the PC is off.

Just recently, when I shut off the power there appears to be a shot of power for about 1/2 second. The light on the front of the PC comes on then off and I can hear the fans giving a quick shot. This morning, before starting up, I turned on the power, left it on about 10 seconds and turned it off. The same thing happend. I'm wondering if this could be a potential power supply failure developing.

The power supply is a PC Power & Cooling 450 W unit about 3 to 4 years old. The rest of the system is as below:

Asus P4P800 SE, 2 G RAM
CPU: Intel Northwood 3.06 P4
HD: One 80 G ATA Maxtor
1 DVD-RW, 1 CD-R
No audio card

Thanks a lot for any thoughts. This is my business PC and I try to stay ahead of its problems.

--Bob

Yes, the 'power block' is a box plugged into my UPS (which is always on) with 6 switched outlets. I had not thought of that. Very good suggestion!

Thanks, I'll give it a try!

--Bob