energy costs

[Richard Walsh]

Dean Johnson wrote:

>Its rated at 13 GFLOPS/kw and Compute Density of 25 GFLOPS/ft^2

To put a finer point on it ...

it being the Cray X1. These are peak numbers and do not include
the square footage and power required by the IO susbsystem. If
you add 8 square ft for IO and assume 25% of peak performance from 
memory you get about 4 Gflops/kw and 5 Gflops/ft^2.  The machine
stands about as tall as a full height rack.  

Regards,

rbw

PS Pentium 4 sustained performance from memory is about
   5% of peak (stream triad).
#---------------------------------------------------
# Richard Walsh
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