Dutch hardware hacker, Emile Nijssen (nickname Mux), claims he has built the world’s most efficient high-end desktop computer: An Intel Core i5-3570K with 16GB of RAM, 64GB SSD, and other assorted bits, that consumes just 5.9 watts when idling and 74.5 watts at full load. Your desktop PC, by comparison, draws around 30 watts while idle and 150 watts at full load (while playing Angry Birds, or surfing a Flash website).

Mux has a bit of a history when it comes to ultra-efficient computers: He built a 50-watt computer in 2008 (called Dennis), a 20-watt computer in 2010 (Dennis2), a 9.5-watt NAS last year (Floppy2), and now the 5.9-watt Fluffy2. Fluffy2 is currently just a headless motherboard, but it will eventually be built into an IPS LCD display to create a passively-cooled all-in-one PC that draws less than 20 watts — the most efficient high-end PC in the world. It’s worth noting that none of these figures include a discrete graphics card, but Mux points out that the i5-3570K finally has an integrated GPU (the Intel HD 4000) that can play most games — at a low resolution with no checkboxes enabled, of course.

How does one go about building a 5.9-watt computer? Well, fortunately Mux is one of those hardware hackers who takes lots of photos, produces his own illustrative diagrams and graphs, and records everything that he does in minute detail.

For a start, Fluffy2 is based on Intel’s DQ77KB mini-ITX motherboard and the Core i5-3570K CPU, which he then pairs with 2x8GB of of DDR3-1333 Crucial RAM, 64GB MyDigital SSD, Intel Ultimate-N WiFi card, and a Logitech wireless receiver. As-is, mostly thanks to Intel’s 22nm Ivy Bridge architecture, Mux says this is one of the most efficient PC setups possible, drawing just 11.6 watts when idle. To go from 11.6 to 5.9 watts — almost exactly half the power consumption — is rather impressive, though.

To do this, Mux does one thing that many of us have tried (undervolting) and one thing that you’ve probably never even considered: Modding the motherboard to be more efficient. Mux begins by analyzing the DQ77KB motherboard to discern the flow of power around the board, and the relationship between each of the components, yielding this diagram:

Then, using his well-equipped electronics lab, he works out how much power each component on the motherboard uses, including the all important conversion losses — the amount of electricity wasted as heat energy when power has to be stepped down from 12V to 5V, 3.3V, and around 1V for the CPU. He turns this data into a proportional diagram, and then a beautiful Sankey diagram:

With this data in hand, Mux went to work on the motherboard, adding a CPU voltmod other various voltmods — and then desoldering the PCIe slot, fan header, SATA ports, and an LED, to further reduce power consumption. The end result, if you look pretty closely, is pretty messy — including a few scorched components — but you can’t argue with a 50% reduction in power consumption. While the reduction in idle power consumption is the most important (most home/office PCs are idle 90%+ of the time), the 25% reduction in max load consumption (99.6W down to 74.5W) is also very significant.

It makes you wonder just how much power (and money) we could save if every computer was as efficient as Mux’s. It’s not like his modifications were particularly complex; Intel and other mobo makers could easily replicate Fluffy2 and bring such motherboards to the mass market. We are already seeing this at a data center level, with big web companies such as Google developing their own, highly-efficient hardware — and of course, when it comes to mobile PCs, reducing power consumption is one of the industry’s prime focuses.

In the future, Mux will post more details about Fluffy2, including detailed guides on how to perform the voltmods yourself, the home-brew UPS (built from a bunch of laptop batteries), and the case for the all-in-one computer (video below).

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