Small PCs feel the nForce2

The growing trend towards smaller PCs got a fillip on Tuesday when motherboard manufacturer Shuttle launched its long-awaited small form factor PC based on Nvidia's nForce2 chipset.

The significance of the launch is that the Shuttle motherboard within the PC uses the version of Nvidia's chipset that has integrated graphics, in the shape of the GeForce 4MX graphics processor, capable of driving dual VGA displays. Previous small form factor PCs from Shuttle -- collectively known as XPCs -- have used less powerful VIA graphics (for versions housing AMD processors), or SIS graphics (for those with Intel processors).

"When we originated the XPC concept, we could only dream of chipsets like the nForce2," said Ken Huang, director of XPC development at Shuttle. Use of the nForce2 chipset enabled Shuttle to build in an 8x AGP slot for upgrading the graphics, as well as USB 2.0 ports. Three Firewire ports are also included.

As integration increases -- networking, USB, Firewire and sound as well as graphics are all now routinely built into the latest motherboards -- small form factor PCs have increased in popularity.

Shuttle's XPCs are among the most high-profile example of the genre. This latest XPC -- dubbed the SN41G2 -- is like previous models about the size of a shoe-box, at 295mm deep by 200mm wide by 180mm high. And in keeping with XPC tradition it is supplied as a "bare-bones" system, which means buyers get a system case with power supply, motherboard and cooling. Processor, memory and drives have to be bought separately, though some PC vendors do sell complete XPCs under their own brands. Shuttle is suggesting a retail price of £250 ex. VAT for the SN41G2.

The small size of XPCs and other small form factor PCs does bring with it problems; notably how to dissipate the heat. As more electronics are crammed into a smaller space, the problem of heat dissipation becomes more critical as the power density increases; from 6.5 watts per litre in a typical Micro-Tower system, to around 13 watts per litre in a small form factor PC.

Everything from the shape and orientation of the processor heatsink blades and the size and speed of the cooling fans, to the size and shape of the ventilation holes have an effect on cooling. Even internal cabling can make or break a small form factor PC.

According to Intel, one of the key factors for introducing the Serial ATA hard disk connectors, which will replace the fat ribbon cables found in most of today's PCs, is to make it easier to build small form factor PCs. Aside from the smaller surface area of cables, which aids air flow through a system, Serial ATA also enables lower voltages in the in supporting chipsets. Intel, the largest manufacturer of motherboards, predicts that Serial ATA will be almost ubiquitous in desktop PCs by the end of 2003.

Shuttle copes with the heat problem using its patented Integrated Cooling Engine technology (ICE), which uses heat pipes to channel the processor's heat directly to a fan at the back of the case. Heat pipes are sealed metal tubes that contain a wicking material and a small amount of liquid in a near-vacuum to channel heat quickly and efficiently. They are commonly used in notebook PCs, but Intel does not accommodate them in its small form factor platforms, saying they are too expensive for mass market desktop PCs.

VIA, the Taiwanese motherboard maker which is also making waves in small form factor PCs, is addressing the problem by decreasing the power dissipation from the C3 processor and associated components on its mini-ITX EPIA M motherboards.

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