Think virtualization in a data center, and you most likely think of the latest generation of multi-core chips, such as Intels recently released Nehalem-EX processor, which comes with eight cores a a whopping 2,300,000,000 transistors. But the future of green data centers may be in the opposite end of the spectrum, with server clusters built using many small, power-efficient processors.

The Power of Software blog gives a very good rundown about the possibility of using small computers and processors instead of large ones like the Nehalem-EX. It mentions the Dell XS11-VX8, also called “Fortuna.” The Via Nano powers Fortuna, and it is a 64-bit chip that offers hardware virtualization for Hyper-V. Amazingly, it uses only 29 watts when at full load, and 15 watts when idling, according to the blog — less power than a UPS uses. Load up plenty of these devices and you can get plenty of computing power, while using not much electricity.

There is been talk for a while that the low-power Atom chip, used primarily to power netbooks, can be used for data centers as well. The blog points out that Microsoft Research has already built two server clusters using Atom processors controlled by the Marlowe control system that in the blogs words, ””””can place servers into the sleep or hibernate low power states and then wake them up. This dynamic state control enables groups of computers to respond to changes in load very rapidly.””””

Will you be using Atom chips and Fortuna today or in the near future to power your data center? Most likely not. But do not be surprised if you do a little further on. Just as smaller servers replaced big iron mainframes, one day devices like Fortuna and the Atom chip may power data centers, and save plenty of electricity while doing so.