I measured another system at the office today looking at usage on a 2950 with Energy Smart power supplies, and L series processors (50W each).
Idle usage was 2.1A, and when I pushed the system as hard as I could to light up 4 cores the system went to 2.9A of power. This is .3A higher than the PE2900 system I am looking at deploying.
There were 2 differences, first, L5410 processors – 2 of them and not just one. The E5420 used in the 2900 is 80W, the L5410 (and L5420) are 50W each. That 50W *could* account for ~0.43A of power at 115V.
Second difference – 6 7200 RPM SATA disks vs the 4 15K SAS disks in the 2900.
I’ll continue to see if I can get an even closer match to test against, but I am beginning to wonder if I should drop the whole idea of the 2950 with L series processors just because the cost savings in power do not rack up enough to cover the much higher cost in the server ($450-$700).
EDIT: Updated from .23A to .43A as the difference for 50W CPU at 115V – bad math!