Using an Intel i5 quad core, I switched from 32-bit Mint 14 to 64-bit Mint 15. I notice the CPU temperatures, as measured by "sensors" are about 10 C lower when idle (down from 43 to 33 in a room temperature of about 22).

Is this to be expected, and why?

Thanks for any advice.

#Get CPU temps first
core0=$(sensors | grep "Core 0:" | awk '{print substr($3,2,4)}')
core1=$(sensors | grep "Core 1:" | awk '{print substr($3,2,4)}')
core2=$(sensors | grep "Core 2:" | awk '{print substr($3,2,4)}')
core3=$(sensors | grep "Core 3:" | awk '{print substr($3,2,4)}')

This has nothing to do with the switch from 32 to 64 bit, but with the switch from Mint 14 to Mint 15, which uses a newer kernel. Intel is has made quite some changes to the code for power management on newer Core i-CPUs (Sandy-/Ivybridge and Haswell).

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My cheap dual core Pentium B960 uses Sandy Bridge and runs cool as a cucumber too. You might find cpu frequency scaling fails completely on older hardware like my AMD Turion Ultra, however. Might make sense to use old kernels and drivers with old hardware and new with new. Backwards compatibility testing just isn't being done I guess. Linus probably hasn't used anything under 1 GHz in a decade.

Well, part of it might be the 64 bit switch. One of the choices made for 64 bit was it didn't have to include any of the very old legacy machines in many of the apps and drivers. So some configuration settings have been made with only 64 bit systems in compile. Some apps and drivers were made for 64 bit with newest compilers and faster running code.

As above the newer kernel had a lot of choices when it was built too that didn't need to include legacy systems.

While the memory use may have increased the actual use of resources has gone down.