[OT] CPU temperature monitoring?

I bought this desktop 4-core machine during the coolest part
of the year and until very recently I could barely hear the
CPU fan except for about one second during power-up when
the fan spins way up and then quickly slows down.

Now it's hotter than Hades here and I'm very much aware of
the fan noise, but I can't tell if the fan is beginning
to fail (the noise sounds a bit harsh to me) or something
is merely controlling the speed appropriately.

The machines BIOS has no settings whatever concerning the
fan or temperature warnings, etc. so I have no idea how
to find out the CPU temp.

The k10temp kernel module loads automatically at boot with
no errors, so I just hope something (somewhere) is taking
care of this stuff automatically.  But I'm only hoping,
not knowing.

Any ideas how to find out for sure?