[Beowulf] Interesting google server design

Prentice Bisbal prentice at ias.edu
Thu Apr 2 11:04:50 PDT 2009

Greg Lindahl wrote:
> On Thu, Apr 02, 2009 at 10:11:07AM -0400, Prentice Bisbal wrote:
>> Or it could be because they make motherboards that convert 12 VDC to 5
>> VDC on the motherboard.
> All Itanium and some other x86 boxes take a single 48V input to the
> mobo. I talked to a mobo designer once and he claimed that there was
> no power savings to be had doing this. Beats me, mon.
> -- greg

High-voltage, low-current lines do have less resistive losses than
lower-voltage higher-current lines (Power loss = current^2 *
resistance). That's why power transmission lines are very high voltages
and low current.

However, I would imagine this is a trivial amount at 12 VDC vs 5 VDC and
the incredibly short distances the electricity travels on a PCB trace.
Google claims that it saves power, so someone at Google must have
obviously researched and measured this.


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