Mystery Alarm on EP45-UD3L

I get an audio tone from my EP45-UD3L during periods of heavy lifting -
sometimes intermittent, sometimes steady.

Right now, running an app called HandBrake which is transcoding DVD to
..MPEG4 disc-to-disc, the alarm is steady. CPU use is pretty much pegged
in the very high nineties per Process Lasso.

I kill HandBrake and the alarm stops immediately. No time for core
temps to drop - although they did drop quickly from high sixties to high
thirties within a few minutes.

Fire HandBrake up again and CPU use immediately rises from low teens to
very high nineties and the CPU temps begin to rise - but the alarm does
not come on until about five minutes later when it starts intermittently
and becomes steady within a minute. Core 0 at this point is running at
69-70 C. The other 3 cores are in the low sixties.

Seems logical that an audible alarm would be for things that threaten
the mobo/CPU so I'm thinking "Temp".

But that begs the question of why the alarm stops instantly when I shut
down HandBrake - certainly before the CPUs have had to cool.

??
--
Pete Cresswell