# Dual Athlon MP 1U units

Velocet math at velocet.ca
Sat Jan 26 15:35:39 EST 2002

```On Sat, Jan 26, 2002 at 02:30:04AM -0600, W Bauske's all...
> Velocet wrote:
> >
> > Whats the power dissipation of running dual 1.2 GHz Mp's? How about for
> > 1.33Ghz regular athlons in non-SMP configs as comparison? (As well, how much
> > heat comes off typical power supplies to run these systems?)
> >
>
> My TigerMP XP1600 duals take about 1.7amps at 125v.
>
> Forgot the formula to convert to btu's. Vaguely remember a factor
> of around 3.42. Not sure if that was for Watt's or VoltAmps. Assuming
> a VA is approximately a Watt, 212.5 * 3.42 = 727 btu per system.
>
> At least with that you can calculate your AC load for a rack. Say 40
> 1U's per rack, 29080 btu's. A ton of AC is 12000 btu's. So, 2.5 ton's
> of AC per rack. Course, you have 40x1.7 amps going into the rack for
> a power load of 68 Amps at 125v.
>
> Those that know the real numbers, please correct. A VA is really around
> .7 - .8 watts, so these calculations are high by maybe 20%. Figure
> the extra allows you to plug in the switches/peripherals/servers in addition
> to the nodes.

not to mention the power supplies themselves (or was that part of the

2.5 tons of A/C is required, that sounds right - that keeps the volume
of air involved at neutral temperature (say 68F) - but how many CFM's
of air are required to move the heat off the processors (well, heatsinks)
fast enough to keep them comfortable (I dont know what comfortable is -
50-55C?) Is there a rule of thumb calc for that?

/kc

>
> Wes
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--
Ken Chase, math at velocet.ca  *  Velocet Communications Inc.  *  Toronto, CANADA
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