Is this power efficient?

[tp4tissue]

For steam to use such an intense compression.

They're saving money on bandwidth, sure,  but does this ultimately waste more electricity (in totality) if decompression has to occur on all client machines.

This is on a 4.8ghz 4970k.

[Leslieann]

The cost on your end varies greatly from low spec machines to ultra high end overclocks so that would be difficult to calculate.

Honestly, the bigger reason for that compression is probably in regards to storage, that much data and backup gets expensive real fast, them saving on bandwidth is just a bonus.