When the discussion turns to Small Form Factor (SFF) PCs, the first question that comes to our minds is how the term is being used. SFF means different things to different people. For some, it's any PC smaller than the norm. For others, it's specifically the "shoebox" form factorthe so-called "cube" systemspioneered by Shuttle. (In fact, Shuttle says SFF means Shuttle Form Factor.) Still others consider any PC built around a microATX motherboard and case to be an SFF system. Some True Believers claim that only systems based on Mini-ITX motherboardswhich are so small they can be built into a teddy bear or cigar humidorqualify as SFF PCs.
We think the best way to define SFF is by case volume. The cubic capacity of standard mini/mid-tower ATX cases ranges from 30 to 50 liters. Typical microATX cases range from 10 to 20 liters. The small Shuttle SFF case is 200mm x 300mm x 185mm, or just under 8" x 8" X 12", and has a volume of about 11 liters. Cases designed for Mini-ITX motherboards are smaller still, from 6 to 9 liters. Most people perceive a 20-liter or smaller case as "small" and a 10-liter or smaller case as "tiny." Any case with a volume of 20 liters or less fits our definition of SFF.
Although Shuttle introduced the "shoebox" form factor, it was by no means the first company to produce SFF computers. Soon after Intel introduced the ATX form factor in the mid-'90s, they recognized the need for smaller systems. ATX was soon followed by smaller variantsMini-ATX, microATX, and finally FlexATX. Although Intel produced some Mini-ATX and FlexATX motherboards, those form factors were generally ignored by third-party manufacturers, leaving ATX as Intel's answer for standard-size systems and microATX for small systems.
Shuttle's first shoebox PC immediately struck a chord with gamers, hobbyists, and other PC enthusiasts. It was expensive, ran hot, didn't have much room for drives or expansion cards, and was noisy. But it was small.
Shuttle followed that first SFF system with a continuing stream of new SFF systems based on various proprietary motherboards for the Athlon XP, Pentium 4, Athlon 64, and, most recently, the Core 2 Duo. Shuttle devotes significant engineering and design resources to their SFF systems, and it shows. Until recently, Shuttle SFF systems were the standard by which all other SFF systems were judged.
In the last few years, many manufacturers have jumped on the SFF bandwagon, trying to horn in on the market niche that Shuttle developed. Until recently, most of these clones were pale imitations of the original product. Recently, several of these other makers, including ASUS, Biostar, and EPoX, have begun shipping SFF systems comparable in quality and features to those made by Shuttle. Shuttle no longer has the SFF market to itself.
A lot of people love Shuttle SFF PCs and their clones. We don't, for several reasons. Most of them use proprietary (or at least semiproprietary) components, including the motherboard and power supply. If you want to upgrade your motherboard or power supply, tough luck. You're stuck with whatever the system manufacturer offers in the way of upgrade options, which often isn't much. We might have been able to live with that, but what we couldn't live with was the very high cost of proprietary SFF "bare-bones" systems. SFF systems typically sell for a 50% to 100% premium over the price of an industry-standard motherboard, case, and power supply of comparable quality.
But merely because we don't much like Shuttle SFF bare-bones systems and their clones doesn't mean we think there is no place for small systems. On the contrary, small systems are perfect for many situations, namely anywhere you need a PC that a standard mini-tower system won't fit or would be intrusive. An SFF system is an ideal candidate for a dorm room, a bedroom set-top box, a home theater system, or a portable LAN party system. For that matter, many people prefer to use an SFF PC as a primary desktop system.
In this chapter, we'll design and build the perfect SFF PC.