Mobo Beeps w/HandBrake?

EP45-UD3L.

When I run the video transcoding app "HandBrake" with "Normal" CPU
priority, I get intermittent beeps from the mobo.

Setting it down to "Below Normal" (in Process Lasso's scheme of
things...) the beeps go away almost completely.

Kicking it up to "High", makes Windows XP appear to freeze and the mobo
emit a continuous beep. But XP isn't really frozen, just really,
really, really unresponsive. Click on Process Lasso's UI to reduce CPU
priority, wait a few minutes, and the menu pops.

Looking at the mobo's temps via "SpeedFan", I'm seeing cores 1-4 in the
low sixties C and core 0 up around 67 degrees C. But when I kicked the
priority up to "High" Core 0's temp spiked up to 69-70 degrees and the
other two showed a similar increase.

Based on SpeedFan's temperature graph, I'm guessing it's the mobo and
not the graphics card, but I really have no clue.

Can anybody shed some light?

Mainly I'm wondering if the CPU and/or mobo is getting physically
abused/damaged/worn or the mobo is just telling me that it's not working
as well as it should be.
--
Pete Cresswell