Are Modern PSU Intelligent???

[Grzyb]

Recently My Rig started behaving strangely.....for no apparent reason during operation the PC it switched itself off.....

To cut a long story short I noticed that one of the fans on the Q-tec 450W Dual Fan Gold PSU was not turning , so I thought that the PSU must have a sensing circuit and be shutting down....

I duly returned the PSU to the shop where I bought it from and received a replacement.....

On fitting the NEW PSU....The rig shut down after 3 Seconds of operation.....

Fitting a "spare" "old" 300w PSU caused no problems....Thinking the replacement was "faulty" as well I returned it to the shop...where they tested it out...All was OK.....

This puzzled me...I thus stipped down my entire PC and startred checking each component....

Eventually I found that the On Board Fan from the GeForce 4 TI4200 Graphics card was seized......

I then did a test....by just "powering" up a "bare bones" system with both the 450w & 300w Power Supplys....and the CPU/MEMORY/GRAPHICS Card....

The 450w shut down again after 3 Seconds
The 300w powered up and stayed on, even though the Fan on the Graphics card wasn't turning....

My Question is thus.....

I suspect that ....."NEW" PSU's have built in circuitry which tells it when some peripheral is trying to draw more current that is allowed....

Can NE1 confirm this...Or have any other observations