[57north-discuss] Dell Servers - Calculations etc

[Tony Travis]

On 11/04/14 02:05, Calum Enterobsidian wrote:
> [...]
> These figures use maximum levels for values, actual consumption may
> be less, but if the server is running near 100% then these will not
> be far off. I would not recommend running with the combined power
> supply values being greater than the 2990kW provided by a 13A plug.
> Some overhead for cable heating, allowance for old cabling, etc
> should be left as well.

Hi, Calum.

I've no experience of the Dell systems, but modern PSU's are designed to
be 80% efficient (i.e. 20% of the electricity consumed by the PSU is
dissipated as heat). Most servers use PSU's that are ~50% over-capacity
because of high start-up currents. In addition, typical CPU heat
spreaders are rated at ~100W per socket maximum. This sets an upper
limit to power consumption regardless of how many cores are in the
processor. In practice I observe ~250-350W power consumption (according
to CPU activity) by each of my two dual 2-core (Opteron 2212) processor
servers running with 32GiB RAM and 16 at 500GB disks in each although the
PSU's are rated at 700W. The 2U Opteron 200 systems I donated to the
"Space" draw about 150W each. I think you're right to be concerned, but
I think that your power calculations are a bit on the pessimistic side.

Bye,

  Tony.

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