Small Form Factor Case Comparison Assignment

A small form factor (SFF) is a computer form factor designed to minimize the volume and footprint of a desktop computer. For comparison purposes, the size of an SFF case is usually measured in litres. SFFs are available in a variety of sizes and shapes, including shoeboxes, cubes, and book-sized PCs. Their smaller and often lighter construction has made them popular as home theater PCs and as gaming computers for attending LAN parties. Manufacturers also emphasize the aesthetic and ergonomic design of SFFs since users are more likely to place them on top of a desk or carry them around. Advancements in component technology together with reductions in size means a powerful computer is no longer restricted to the huge towers of old.[1]

Small form factors do not include computing devices that have traditionally been small, such as embedded or mobile systems.[2] However, "small form factor" lacks a normative definition and is consequently open to interpretation and misuse. Manufacturers often provide definitions that serve the interests of their products.[3] According to marketing strategy, one manufacturer may decide to mark their product as "small form factor", while other manufacturers are using different marketing name (such as "Minitower", "Microtower" or "Desktop") for personal computers of similar or even smaller footprint.


The acronym SFF originally stood for "Shuttle Form Factor," describing shoebox-sized personal computers with two expansion slots.[4] The meaning of SFF evolved to include other, similar PC designs from brands such as AOpen and First International Computer, with the word "Small" replacing the word "Shuttle".

SFF originally referred to systems smaller than the Micro-ATX. The term SFF is used in contrast with terms for larger systems such as "mini-towers" and "desktops."[5]


Small form factor computers are generally designed to support the same features as modern desktop computers, but in a smaller space. Most accept standard x86microprocessors, standard DIMM memory modules, standard 3.5-inch hard disks, and standard 5.25-inch optical drives.

However, the small size of SFF cases may limit expansion options; many commercial offerings provide only one 3.5-inch drive bay and one or two 5.25-inch external bays. Standard CPUheatsinks do not always fit inside an SFF computer, so some manufacturers provide custom cooling systems. Though limited to one or two expansion cards, a few have the space for ​34-length cards such as the GeForce GTX-295.[6] Most SFF computers use highly integrated motherboards containing many on-board peripherals, reducing the need for expansion cards.

Even if labeled "SFF," cube-style cases that support full-sized (PS2 form factor) power supplies actually have a microATX form factor. True SFF systems use TFX or smaller power supplies, and some require a laptop-style external "power brick."

Some SFF computers even include compact components designed for mobile computers, such as notebook optical drives, notebook memory modules, notebook processors, and external AC adapters, rather than the internal power supply units found in full-size desktop computers.

SFF types[edit]

The many different types of SFFs[7] are categorized loosely by their shape and size. The ones below are available as of 2013[update].


Many SFF computers have a cubic shape. Smaller models are typically sold as barebones units, including a case, motherboard, and power supply designed to fit together. The motherboard lies flat against the base of the case. Upgrade options may be limited by the non-standard motherboards, cramped interior space, and power and airflow concerns. The Power Mac G4 Cube, released in 2000, and the Shuttle XPC are good examples of this design. MSI and Asus produce similar designs. The Xi3 Modular Computer is an example of a cube computer with a little more upgrade possibilities.

Shuttle has adapted several of its XPC models to alternately accept mini-ITX motherboards. The base of the XPC is provided with mounting points which accommodate both "Shuttle form factor" (ShFF) and mini-ITX motherboards. In order to accommodate mini-ITX motherboards, two of the ShFF mounting points are simply relocated (the other two mini-ITX mounting points are in common with ShFF mounting points). A "standard" ShFF motherboard is 8 1/8″ wide by 10 3/4″ deep, with the I/O shield and the two PCI slots being located in common with mini-ITX motherboards. Most ShFF systems utilize Shuttle's proprietary heat pipe (liquid) cooling system, "Integrated Cooling Engine" (ICE), for the processor, although several also feature heat pipe cooling for the voltage regulator or the chip set (Northbridge). When the ShFF motherboard is replaced with a mini-ITX motherboard, an Intel or compatible fan must replace the ICE unit. The ShFF's ICE fan is so designed that it may be repurposed as a case fan when the case has been converted to mini-ITX use: the special fan retaining screws are used in place of the ICE unit's thumb screws.

AOpen Inc. produced a stackable S120[8] case, allowing the user to stack up to four components vertically or horizontally. These layers can be for add-on cards, optical drives, and hard drives, using either internal power supplies or external AC adapter power sources. After the S120, AOpen made more small form factor cases for systems with Micro ATX and Mini-ITX.


Main article: Nettop

Until 2005, SFF cases were usually sold as barebones units (case, power supply, and motherboard) to system integraters and home-based builders. In 2005, Apple Inc. introduced its Mac Mini (volume of 1.4 L, excluding external power brick). Later in the same year, the first AOpen mini PC MP915 (renamed to XC mini in 2007 since "mini PC" could not be registered as a trademark), was announced. The size of the XC mini series PC -- 165(W) × 50(H) × 165(D) mm -- makes it one of the smallest desktop PC systems (1.3L volume). It was criticized for looking like the Apple Mac Mini, but Apple has not taken action on this subject. In February 2007, AOpen redesigned the case of the mini PC MP945 series.

Since 2006, major OEM PC brands such as HP and Dell have begun to sell fully assembled SFF systems. These are often described as bookshelf units since they resemble a miniature tower case small enough to fit on a bookshelf. The HP Slimline series and Dell C521 (volume 1.65 L) are good examples of this trend. The Maxdata Favorite 300XS is another mini computer. The HP Slimline uses a non-standard motherboard that is very similar in size to Mini-ITX.[9]

In addition to its industrial use, the extremely small Mini-ITX motherboard form factor has also been incorporated into SFF computers. These are often extremely compact, incorporating low-power components such as the VIA C3 processors. The Travla C134 is an example of this design; it is somewhat larger than the Mac mini (7×10×2" vs 6.5×6.5×2"), and barely bigger than a standard 5.25" optical drive.

Beginning in 2007, several other companies have released other very small computers that besides a small size, focus on a low price, and extremely high power efficiency (typically 10 W or below in use). These include the Zonbu, fit-PC, Linutop, and A9home. With the release of Intel ATOM CPU, AOpen also made Nettop systems: the uBox series with model LE200 and LE210.[10] The uBox series equips a dual core Intel Atom 270/330 processor, single channel DDR-II 533/667 memory, Intel 945GC+ICH7 chipset, three SATA connectors and 5.1channel high definition audio output.

Home theatre boxes[edit]

Essentially a bookshelf-style case lying on its side, a miniature HTPC replicates the look of other smaller-than-rack-sized home theatre components such as a DVR or mini audio receiver. The front panel interface is emphasized, with the optical disc drive rotated relative to the case in order to maintain horizontal mounting, and more motherboard port connectors (such as for USB) are routed to the front panel, they normally are as powerful as PC desktops.


A computer-on-module (COM) is a complete computer built on a single circuit board. They are often used as embedded systems due to their small physical size and low power consumption. Gumstix is one manufacturer of COMs.

Ultra-Small Form Factor[edit]

Each model of Dell's Optiplex line of computers typically includes an Ultra-Small Form Factor (USFF) chassis option. In the Core 2 era, these machines used 3.5" desktop hard drives and external power supplies, like the Optiplex 745 and 755. More recent units use 2.5" laptop hard drives and have integrated power supplies, like the Optiplex 990 USFF. The compact size comes at the cost of restricted expandability, as USFF models have no PCI or PCIe slots and may have limited CPU and memory options.

Ultra-compact Form Factor[edit]

Understood as comprising nano-ITX (12 cm × 12 cm) and pico-ITX (10 cm × 7.2 cm) boards, the format was championed by Via Technologies.[11] Intel now describes its own Next Unit of Computing (NUC) products (4 × 4 inch, approx. 10 × 10 cm) as UCFF.[12]

See also[edit]


Shoebox case (Shuttle SP35 pro)
  1. ^"Small Form Factor PCs - Fierce PC". Retrieved 2016-10-05. 
  2. ^Joe Rybicki (May 2007). "The Incredible Shrinking Game Machine! Part One: The Small Form-Factor PC". Games for Windows: the Official Magazine (6): 92–96.  
  3. ^SilverStone Technology Co., Ltd. What is SFF (SG03)?
  4. ^
  5. ^
  6. ^Assembly And BIOS : Shuttle’s SX58H7 Ultra-Portable Core i7 Platform
  7. ^"List of Small Form Factors," PC/104 and Small Form Factors, 2008
  8. ^S120 spec:
  9. ^HP and Compaq Desktop PCs - Motherboard Specifications, PTGV-DM (Onyx2)
  10. ^uBox news:
  11. ^"GIGABYTE's Haswell BRIX Lineup Updated with BRIX s Models". AnandTech. Retrieved 2014-01-13. 
  12. ^"Intel® NUC Board D33217GKE". Retrieved 2014-01-13. 

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Specs at a glance: Corsair One
LowestMiddleBest (as reviewed)
OSWindows 10 Home 64-bit
CPUIntel Core i7-7700 (liquid cooled)Intel Core i7-7700K (liquid cooled)Intel Core i7-7700K (liquid cooled)
RAM16GB DDR4 2,400MHz (8GBx2)16GB DDR4 2,400MHz (8GBx2)16GB DDR4 2,400MHz (8GBx2)
GPUNvidia GTX 1070 (air cooled)Nvidia GTX 1080 8GB (liquid cooled)Nvidia GTX 1080 8GB (liquid cooled)
NETWORKINGGigabit Ethernet, AC Wi-Fi
PORTS3 x USB 3.1 Type-A, 1 x USB-3.1 Type-C, 2 x USB 2.0, 2 x DisplayPort, 2x HDMI, headphone jack, microphone jack
SIZEHeight: 380mm (14.9 inches), depth: 200mm (7.9 inches), width: 176mm (6.9 inches)
WARRANTYTwo years with 24/7 support and five day repair turnaround
NotesThere's also a fourth model, which Corsair didn't tell us about ahead of time, with a GTX 1080 Ti. It's an online exclusive priced at £2600/$2700. Still no M.2 SSD though...

It's hard to believe that the Corsair One comes from the same company that designed the Bulldog, a small form factor PC so monstrously ugly that the mere thought of placing it in a living room was enough to set off a spousal gag reflex. Where the Bulldog was a confused mishmash of jaunty, l33t gamer angles, the One is sleek, sophisticated, and—dare I say it—even a little grown up.

That Corsair continues to sell a slightly updated version of the Bulldog is something of mystery considering just how good the Corsair One is. Of all the small form factor (SFF) PCs I've tried—and there have been quite a few over the past year—it is by far the best. I'd even go as far to say it's one of the best pre-built PCs you can buy, full stop.

At £2,300 for a fully loaded version, the Corsair One isn't cheap by any means—and as always, going the DIY route can lead to substantial savings—but few homebrew PCs have such a tiny footprint. Fewer still do so while being entirely liquid cooled, graphics card and all. It's a combo that results in a PC that doesn't just fit into the living room environment aesthetically, but acoustically too.

And, unlike the entirely custom hardware of the Zotac EN1080, you can even upgrade it.

Dual radiators FTW

Well, sort of. The Corsair One does indeed feature standard hardware. Inside is a mini-ITX motherboard by MSI. There's one of Corsair's 400W, 80 Plus Gold rated modular SFX power supplies, two sticks of Corsair Vengeance 2400MHz DDR4 RAM, and a socketed Intel Kaby Lake 7700K processor. A riser cable wraps around from the single PCIe slot to the backside of the motherboard, where there's space for a triple-slot graphics card. Extension cables then bring HDMI (1x) and DisplayPort (2x) to the rear of the case.

But in the fully loaded version of the One, both the GTX 1080 graphics card and the CPU are liquid cooled by two separate all-in-one 240mm radiators, which flank each side of the One's case behind vented aluminium panels. Corsair doesn't intend for the One to be user serviceable—although getting inside just involves pushing a button and undoing four screws—but replacing the CPU is an easy enough task, as is upgrading the 2.5-inch SATA SSD, which sits insides a simple plastic slot.

    It's unlikely, especially if the rumoured roadmaps for Intel's Coffee Lake architecture hold water—that anyone would want to upgrade the CPU in the near future, but the graphics card is a different story. You can already buy a GTX 1080 Ti, and in year's time both Nvidia and AMD will have entirely new architectures on the market. The MSI-made graphics card is cooled in a similar fashion to the CPU, with a 240mm radiator. But as anyone that's tried to fit a liquid cooler to a graphics card can attest to, it's a far more involved affair than replacing a CPU, particularly since the VRMs and memory modules still need to be air-cooled.

    If you're skilled enough, it may well be possible to swap out the GTX 1080 for another Nvidia card with a similar board layout and keep the same cooler. Or, you could just ditch the liquid cooling entirely—or opt for the cheaper air-cooled version of the Corsair One—and install a blower-style card. But doing so ruins one of the best things about this PC: this is by far the quietest SFF system I've ever used.

    You might have noticed the lack of mention of any fans, and that's because the Corsair One has just one. At the very top of the case is a single 140mm fan—one of Corsair's fancy magnetic levitation fans that promises quieter operation—which relies on assisted convection to draw air through the side panels, over the radiators, and out of the top of the case. It's similar to how Apple keeps the Mac Pro cool, but by using radiators and liquid instead of a central heatsink.

    It works extremely well.

    I don't have a way to test sound levels here in the office (consider it something we're thinking of adding to our tests), but Corsair claims that in an anechoic chamber it recorded an idle noise level of 20dBA, or about as loud as a whisper from three feet away. The system is certainly more audible while gaming if you're sitting right next to it, but over a larger distance (such as in the living room), or perhaps in a closed cupboard, you'll hardly notice it.

    In both cases, the fan sound is soft and dull and quite unlike the high-pitched whine of a PlayStation 4 or Xbox One.

    Listing image by Mark Walton

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