[Beowulf] XEON power variations

Bill Broadley bill at cse.ucdavis.edu
Wed Sep 16 13:36:40 PDT 2009

Tom Rockwell wrote:
> Hi,
> Intel assigns the same power consumption to different clockspeeds of L,
> E, X series XEON.  All L series have the same rating, all E series etc. 
> So, taking their numbers, the fastest of each type will always have the
> best performance per watt. 

Wrong, well they might.  But not because the power use is the same.

> And there is no power consumption penalty
> for buying the fastest clockspeed of each type. 

No marketing visible penalty.  Intel doesn't want you buying their low profit
cheap chips instead of the high profit expensive chips because of the power
you save.

> Vendor's power
> calculators reflect this (dell.com/calc for example).  To me this seems
> like marketing simplification...  Anybody know any different, e.g. have
> you seen other numbers from vendors or tested systems yourself?

Try silicon mechanics, their configurator shows the system power for different

 > Is the power consumption of a system with an E5502 CPU really the same
> as one with an E5540?

A random dual socket at SI shows 197 watts for a 5502 and 259 watts for a 5540.

Intel/AMD often just bin them by power for marketing reasons.  It's just funny
business.  So for instance the 3 new lynnfields are <= 95 watts, yet in
testing the slowest is more power efficient they their "efficient" line which
includes the 9550S which is rated as under <= 65 watts.

So while intel isn't lying, it seems clear they are avoiding posting real
numbers to make the faster clocked cpus more attractive.

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