Over the last couple of years, a minute part of computing history, the market and ‘modding’ communities have slowly become aware of the feasibility of smaller, more efficient computer systems.
Over the course of this article, I will endeavor to decipher the current situation, as well as make a few suggestions as to where I think we as a community should be heading. As always, this is my personal opinion, so take it with a grain of salt! Courtesy of Wikipedia: “A small form factor (SFF) is a computer form factor designed to minimize the spatial volume 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.” LOSIAS.net’s general description: A PC that is small (under 20 litres) or smaller than it should be, for example an E-ATX board in a mid-tower Chassis, or a M-ATX board in an ITX chassis.
Smaller form factor PCs have always existed, from the original Apple desktops to the first generation of Shuttle PCs to the latest HP Slimline PCs. There is also a growing aftermarket and DIY (Do It Yourself) market for SFF hardware. It’s all about efficient use of space, energy and sound. All three factors that, if minimized, make an excellent small form factor PC.
We don’t call it small form factor without good reason, the space a system takes up is important. Going small can be for various reasons, smaller desk space, portability (LAN parties), hiding a system or for a subtle HTPC. “Bigger is better” no longer applies in the computing world with extremely powerful graphics cards taking up less room, multi-core processors producing less heat and the onset of new concepts in power supply. When choosing a home for your new, or used (eBay can throw up some great bargains, and is home to many a wacky/weird SFF component!) bits, the sky’s the limit…as long as it’s small.
Lian Li, Silverstone, Thermaltake and many more manufacturers make small form factor cases these days, of course with variable quality and design. Try to buy your components before your case, as trying to make it all fit, a much bigger issue in SFF, could be a challenge! The best way, although much more difficult, is to build your own. Building a chassis from scratch is a long process, but the result is well worth it. The final product is just as you want it, one of a kind, and much more satisfying to behold as the owner. In the forums we support scratchbuilds and mods alike, both are awesome ways to have a one of a kind SFF rig. The major consideration in case design is the cooling of the components. A tiny case is awesome, but is effectively useless if it can’t handle the heat load put out by the components inside. At the very least you will have an unstable, hot system with a reduced lifespan and at worst, you will kill your components!
Cooling design can be as simple as intake and exhaust fans, and as complicated as squeezing a liquid cooling system into the chassis. Most people opt for air-cooling, as unless careful consideration, and usually a lot more money, is put into a liquid cooling setup, the result is poor. Even with air cooling, we have to look at positive vs negative pressure, filtering, direction, convection, and noise. We will cover more chassis/case design technical considerations and options in future articles.
Power supply units (PSUs) now come in various forms, from the regular, admittedly massive, ATX form factor products down to the tiny Pico-PSU, which takes up not much more space than the 20/24 pin connector on your motherboard. There are many in between sizes, M-ATX (aka SFF), TFX, SFX, as well as the token, proprietary units from OEMs such as HP. All of these units can power your SFF system, assuming it can supply enough juice, and the wiring isn’t ‘unique’ like some of the proprietary units. The decision to make here is what you can afford and what can fit in your case.
ATX Power Supply
ATX power supplies generally have the dimensions of 150 mm (W) x 86 mm (H) x 140 mm (D) and share a common mounting layout of four screws arranged on the back side of the unit. The issue, in regards to SFF systems, with full ATX power supplies is their size, being an overly large form factor to support the full range of power capacities available, as well as being compatible with the massive quantity of full sized ATX and micro-ATX compatible cases.
SFX is a form factor for a power supply casing and the power specifications are almost identical. This size is also commonly referred to as Micro-ATX power supplies. Dimensions are typically 125 mm (W) x 63.5 mm (H) x 100 mm(D). Silverstone, FSP and Seasonic are recognized as the main supplier of quality SFX power supplies. Apart from these branded units, I haven’t been able to find much range in this size segment other than OEM 100-200watt units.
Another small form factor power supply with standard ATX specification connectors. Generally 83*mm (W) x 64*mm (H) x 146 mm (D)
Similar to 1U size, a very ‘skinny’ power supply. 81.5 mm (W) x 40.5mm (H) x 150mm (D) in size, this is more suitable for thin cases like HTPC’s and desktops. The main issue with these (and the 1u power supplies) is the need for 40mm fans for cooling, which have to spin fast, and therefore noisily, to move enough air to cool the unit.
1U (server) PSU
Similar to Flex-ATX, but 100-106mm wide. Generally these are available with a higher wattage rating, but this usually leads to higher fan speed on those nasty 40mm!
Available from 60 to 150 watts, this power supply relies on a 12v input from an external power brick of sufficient amperage. Due to the fact that this particular form of power supply has such a low wattage capacity, it is recommended that you don’t use a graphics card that requires an external power source (such as the 6 and 8 pin plugs that supply 12v directly to the card). Lower end graphics cards under 75 watts (HD5670/HD6750 and the like) are powered by the motherboard, so are acceptable IF the selected Pico-PSU can supply enough power for the entire setup.
CPUs are constantly being developed and revised to be more powerful, yet more efficient. Models available from AMD, Intel and VIA cover a broad spectrum of uses, HTPC to office PC, LAN rig to home server. Here’s but a few models available suitable for the SFF end of the market and their suggested uses: VIA processors – generally much lower performance and core count than their AMD or Intel counterparts, these processors only come embedded onto motherboards, preventing any future upgrades. These processors are mainly designed for very low wattage desktop PC’s, as their performance is generally good enough for media processing, and is incredibly lacking when it comes to gaming.
Embedded CPU (soldered onto the motherboard, can’t be upgraded). These are very low power, and available up to 1.8ghz with 2 cores. Intel’s Hyperthreading technology takes this to 4 logical cores. Suitable for HTPC, small business and home office, and home server use.
AMD Sempron & Athlon
Available from single to quad cores, 1.8ghz to 3.2ghz. Sempron is AMD’s low end CPU for socketed boards, while Athlon is the mid-range CPU. Sempron is suitable for similar situations as the Atom. Athlon can cover those bases, but generally has higher performance than the Sempron, at the expense of power usage and heat output. More suitable for a higher end HTPC or mid-range LAN gaming rig.
Intel Celeron & Pentium
Originally Intel’s low and high end processors, the introduction of the Core i3/i5/i7 range has relegated these model ranges to the low and low-mid range. These are similar in performance to the Sempron and Athlon above, respectively.
Intel Core i3
Intel’s low to mid range processor. Some Core i3 processors include Intel’s Hyperthreading technology, so can have up to 4 logical cores. Seen by many as Intel’s competitor to the Athlon range. Covers the home office and low end gaming range. The integrated graphics on the i3‘s core is also sufficient for a mid-range HTPC, negating the need for a power hungry and heat producing discrete graphics card.
AMD Llano APU
This processor from AMD is based on the K10 generation Athlon core, with a Radeon GPU core attached. This leads to a processor that, while admittedly slower on the CPU side of things versus the i3, is much faster in the graphics department, leading to a processor that is very suitable for HTPC duties, as well as a lower end gaming machine (the Quad core A6 can play Left4Dead2 at 35-45 frames per second at 1280×1024 resolution on the integrated graphics!)
Intel Core i5
Intel’s mid to high range processor, the Core i5 is suitable for higher end uses – gaming (with a discrete graphics card), video encoding, and a home server that is expected to serve more than files. The Core i5‘s integrated graphics is at a higher level than the i3‘s but is still insufficient for gaming. This range of Intel processors does not include Hyperthreading, so you do not get any ‘bonus’ cores.
AMD’s high end processor of the K8 and K10 generations. More suitable for a SFF PC than Bulldozer (see below) due to having lower wattage products available within the range. The Phenom comes with 2 to 6 cores, and from 65 to 125 watts. Depending on use, budget and luck (some Phenom II x2‘s can be ‘unlocked’ to x3 or x4, and some x4‘s unlocked to x6, luck of the draw, no guarantee here), there is a whole range of processors for various uses here.
Intel Core i7
Intel’s high end processor, incorporating higher clockspeeds and Hyperthreading, this CPU is ideal for gaming rigs and media encoding.
AMD’s freshly released processor. This uses Socket AM3+. Due to it being a brand new architecture, Microsoft Windows with its long release schedule cannot take advantage of the architecture. Unless you are running multicore-optimised programs in Linux (media encoding, rendering, etc) I would recommend going for the K10 Phenom II range if you wish to buy an AMD CPU.
Motherboard Form Factors
When building a traditional Small Form Factor PC, the general consensus has been to use Micro-ATX, Flex-ATX, Mini-ITX or any of the many proprietary boards available.
Generally 244mmx244mm, Micro-ATX has been the standard for smaller PC’s for over a decade now. Available with most CPU sockets, expansion slot options and in various colours and designs, this is the go-to board for higher-end SFF rigs. It is even possible to find SLI or Crossfire compatible M-ATX motherboards! Most M-ATX boards have much more IDE/SATA ports than their M-ITX counterparts, making this sized board a better option for a home file server.
This is a standard introduced mid-way through the last decade by VIA, designed for their low wattage processors. Other board makers have taken the form factor and infused it with the options and performance available on the larger motherboards, albeit within limits put in place by the size of the board. Both AMD and Intel sockets are available on these boards, enabling DIYer to create a powerful PC in a tiny space. Limits such as the single expansion card slot, CPU power available and the limited ports for drives can reduce the pros of this form factor, but depending on the end-use the advantages may outweigh the disadvantages. Most M-ITX boards include a network jack (or two!), a single expansion card slot (PCI, or increasingly PCI-Express), 5.1 to 7.1 channel audio (some boards even offer optical and SPDIF outputs for the connoisseur), 2 RAM slots and much more. Due to the dimunitive size, the space for CPU power phases is limited, so most ITX boards are limited to 95 watt processors. Core unlocking for AMD Phenom II processors is a rare option, and overclocking in general is very limited by the board’s inherit lower ability to provide power.
There are other form factors available, Pico-ITX, nano-ITX and so forth. Generally these are limited to the lower performing but lower wattage VIA CPUs and expansion is very limited.
Graphics cards are constantly evolving to be more powerful yet more efficient. Offerings from both nVidia and AMD (and ATI before AMD purchased the company) cover everything from low power HTPC cards and IGP replacements to whole-hog light-dimming nutters that make M-ITX boards look like postage stamps. Your choice here is limited by once again budget, as well as the size of the chassis that it will be implemented in. The big limiter however is the expansion card slots available on the motherboard. AGP, PCI and PCI-express are not inter-compatible (even considering the confusingly similar names of the latter two) so you must choose wisely. At the low end of the scale, both nVidia and AMD/ATI offer low profile, passively cooled cards through their manufacturing partners. These are ideal for HTPC’s and efficient, small gaming PC’s. Let’s face it, you don’t need the power of a discrete card for office duties!
The current preference is for the ATI Radeon HD4550, HD5450, (AMD) HD6450, and nVidia GT220, GT430 and GT530. All seem to be available in the low profile design with various passive and active coolers. Larger, more powerful graphics cards can be used in SFF PC’s, its just a case of if your PSU is up to it, and if your case can fit it and handle the heat. In further articles I will cover the above information in more detail, so stay tuned.
As a SFF connoisseur, I do have a few issues with where the market is at the moment: -The lack of decent SFF orientated power supplies. The only ones available on the market are either cheap, nasty OEM models or incredibly expensive premium models. We need a range, like the ATX PSU market where you can get a product over a whole range of pricing. -More cores per watt! I render and design a lot, quite a few others encode a lot of media, we need hex cores or octocores under 75 watts! (both for cooling performance and overclocking headroom). Here at LOSIAS we don’t define SFF by the board size, in fact a few members have built SFF grade rigs from full sized ATX boards, and at the extremes, I built a SFF PC from an extended-ATX board in a scratch-built case that was half the size of a Mid-Tower! It’s not the board that matters, it’s the intent.