The Motherboard Buyers' Guide

Upper board spacing, restrictions and layout
An important consideration for a motherboard is the placement of all the differing components and pieces that come together to make a single, unified and functional motherboard. There is so much to keep in mind when determining the component layout for the board: what parts will restrict others, how much space is needed between two given points and an ever increasingly important thought is whether the end result is functional from a system building perspective.

It’s obviously important, but what kind of layout considerations should a prospective buyer be mindful of and looking for? One such is the space available between the CPU socket and the edge of the memory DIMM slots. If the socket is too close this could result in compatibility issues with third party heatsinks and/or be a hindrance due to the need to remove the CPU cooler to simply remove or adjust the DIMMs. An additional worry for third party heatsinks, or at least what orientation they can be placed in, is the distance the CPU socket area resides from the top edge of the motherboard PCB.

Another important restriction to be mindful of is the possible issues from large North Bridge and VRM (volt regulating MOSFETs) cooling. This can be due to large passive heatsink skyscrapers or from oddly intertwining heatpipe jungles. This particular issue isn’t so much a problem in the current market as past faux pas have both taught offending manufacturers and in turn taught the competition what is acceptable and what is not. None the less it’s worth being mindful of this and if there is concern regarding the compatibility of a given motherboard and heatsink combo, be sure to check out enthusiast forums for some user feedback. If this cannot be obtained, use the contact details listed on manufacturer websites to obtain support for the question – assuring you obtain two products happy to play ball with one another.

If you’re the type to tweak and fiddle with the setup of your system a spacing consideration worth giving some thought is the spacing between the back of a large GPU in the primary PCIe 16x slot, for example the 8800GTX, and the fully extended length of the clips used to secure the DIMMs in place. As small as this may sound, there is nothing more frustrating than having to completely remove a GPU simply to add/remove sticks of memory.

The EIDE, or commonly referred to as ‘that plug I put the cable in for my optical drive’, is slowly but surely being phased out. None the less, as affordable SATA optical drives flow into the market, the legacy PATA optical drives, and even HDDs for some individuals, still need to be hooked up to the system. This means large cumbersome PATA ribbon cables need to be accommodated and as such, good placement of the EIDE connection is important and on a good board is generally kept to the upper right edge and grouped with the ATX 24-pin power connection.

This brings us to the next area of consideration for the upper sections of the motherboard’s layout – the power connections. The common connections for a motherboard’s power supply are through the ATX 24-pin and EPS 8-pin connections. It is not limited to this, however, some boards supporting multiple GPUs also include an additional 4-pin power connection for further power supply to the board’s circuits to help maintain smooth power flow and management while under the strain of an additional GPU. Good placement of the power connections can make for much easier cable management within a system.

Look for boards with the ATX 24-pin along the upper right hand edge of the motherboard and the EPS 8-pin connection in the upper left corner behind and between the rear I/O ports and CPU socket area.

Lower board spacing, restrictions and layout
Moving onto the layout of the lower portion of the motherboard there is a distinct bias towards one particular design. This is the placement of expansion slots to the left area, additional and optional I/O connections across the bottom edge (e.g. extra USB and FireWire connections) and SATA ports and additional connections and switches towards the right edge.

When considering the PCIe 16x spacing be mindful of the slot’s relationship with the rest of the expansion slots. Keep in mind the allowance for adequate cooling for single and dual slot coolers. Additionally have an idea of what slots would be effected by large coolers – are these slots expendable or are they necessary?

For example, many manufacturers now place PCIe 1x or PCIe 4x slots below the PCIe 16x slots and maintain the PCI slots above or two slots below a PCIe 16x slot to assure PCI expansion availability, due to it still being the primary expansion slot for the likes of sound cards, network interface cards and TV tuners.

Lastly the spacing between PCIe 16x slots on a motherboard supporting multi-GPU configurations is yet another consideration when perusing for a new board for that monster rig. Is there sufficient space between the GPUs? Will the primary GPU’s cooling mechanism be suffocated or restricted by the close placement of the secondary GPU? The expansion slots may look simply thrown on the board but considerable layout thought must be given.

Now that the necessary considerations have been outlined it’s a matter of seeing what type of layout accommodates your needs. There are generally three options and are largely dependent on other features on the motherboard. These three options are to either utilize five, six or seven expansion slots for the slot layout. Many of the mainstream boards now incorporate a six expansion slot setup and with ever growing multi GPU systems, this is getting rather crowded. It’s for this reason that many of the luxury high-end motherboards with support for 3-Way SLI and CrossFire X utilise a seven slot expansion layout, allowing for three GPUs with dual slot coolers to sit side by side, albeit a little on the warm side.

As mentioned, the SATA ports are commonly placed along the right side of the lower region of the motherboard. Placement of these ports needs to be given considerable thought; if a SATA port is placed directly behind an expansion slot inline with a PCIe 16x slot in particular; there is a high risk of losing access to a port or two. This loss of ports is due to the expansion cards extending further back than simply the length of the slot itself. To avoid the issue completely, some manufacturers not only push the placement of the ports to the very edge of the board but also then shift the connection onto a 90 degree angle. This not only avoids the issue of expansion card interference but also adds easier cable management and greater overall system presentation.

For any overclocker that pushes the boundaries of their system, be it for a stable air cooled or water cooled 24/7 setup or looking for the outright maximum with extreme cooling such as dry ice, cascade and LN2, they will undoubtedly become good friends with the CMOS battery and CMOS clear switch. The need for easy access to these parts is extremely important for the overclocker and bad placement of the CMOS battery and CMOS clear switches can make an otherwise well-designed board an utter nightmare to deal with – note to manufacturers: no one likes to have to remove GPUs just to get to a CMOS battery or clear switch. Best placement is often towards the lower right corner of the board, with thought given to extended GPUs and other expansion cards, as well as ease of access when in a full system build.

An ever more prominent inclusion in today’s enthusiast motherboards are switches and buttons to not only control aspects such as CMOS clear but to also give a method to turn the system on/off or reset the system when benchmarking on an open test bed; or any other situation where case switches have not been connected to the front case I/O headers. Again, due to the switches being included in the lower portion of the board layout, it is important to ensure the switches are not obstructed by expansion cards – there’s no use in having easy to use switches/buttons if they’re not easily accessible.