GigaOm has a post on Rackable CloudRack C2 Server.

Rackable’s New Servers Like It Hot

Stacey Higginbotham | Thursday, March 19, 2009 | 7:09 AM PT | 1 comment

Rackable announced today an update to its CloudRack servers. The CloudRack C2 servers can run at 104 degrees inside the data center, and they offload power supply to the rack to reduce energy wasted in converting AC electricity from the wall to DC electricity used by the box to 1 percent. Since these beasts can pack 1,280 cores, or 320 processors, into a rack, they’re not exactly in the power-saving category, but the design ensures that the electricity is going to power the processors rather than lost as heat or waste.

Note Rackable is saying their power supplies are 99% efficient in addition to servers can run at 104 degrees.

What caught my eye though was Intel Atoms would be a future option.

Rackable also announced that customers will eventually be able to build out servers in the CloudRack trays using Intel’s lower power Atom chips, which they can use for jobs that don’t need the full horsepower of the upcoming Nehalem-based Xeon chips. Customizing processors is one more way that data center operators are trying to boost efficiency.

Rackable is trying to be different by using less power.

The rising competition around designing power-efficient, heat-tolerant servers is being driven by a need to lower electricity and cooling costs in a data center contrasted with the need to pack as much computing into a box as possible to run web-scale application increases. Essentially, we need more computing but have less electricity to squander. Rackable can sell into corporate data centers, but its target market is the web world giants running thousands of servers.

Rackable’s web site has more details.

The Power XE™ Difference
CloudRack C2 is the first of many Rackable products to utilize Power XE — a next generation cabinet-level power distribution technology:

Virtually eliminates the data center "stranded power" problem (a data center's power capacity which is paid for, but ultimately unused) and provides nearly perfect phase balancing

Significantly improves power delivery efficiency by converting incoming AC power to 99 percent efficient 12V DC power via hot-pluggable, N+1 redundant rectifiers

Eliminates server-level power supplies and cooling fans for improved reliability

Dramatic Thermal Efficiency
CloudRack C2 is thermally optimized to allow data centers to operate at much higher temperatures, up to 40° C (104° F).

Higher system temperature tolerance means significantly reduced power consumption by Computer Room Air Conditioning (CRAC) units which in turn means radically reduced operating cost.

Thermally managed airflow via redundant, hot swappable, easily serviceable, cabinet-level autonomic fan arrays for better enclosure reliability

Over 80% reduction of fan power compared to conventional AC enclosures