We ran our customary PCMark05 and The Gimp performance tests. One of the NB100's function keys flips between the standard 1.6GHz and an underclocked mode which the netbook's manual suggests doesn't use a fixed frequency, but oscillates up and down, according to the workload.

PMark05 Results

Longer bars are better

Our PCMark05 results for both settings were consistent at each CPU setting, so we'd say the underclock simply drops the CPU speed to 800MHz and keeps it there, otherwise PCMark05 CPU-taxing algorithms would surely cause the code up maximise the clock speed, which the numbers show was not happening.

The Gimp Results

Time in Seconds
Shorter bars are better

The Gimp results are good, though you can clearly see the impact of underclocking the Atom processor and - as the chart above shows - of knocking back the memory speed too.