Layout Considerations

With the components defined we can now take a closer look at how they affect layout, and how layout is affected by them. The Asus motherboard below has several strong features and a few drawbacks that will put things into perspective.

A primary layout consideration is the amount of clearance that graphics cards have to other devices. The example above puts the uppermost PCI Express x16 slot in the second slot position (see the blue slot), providing a small amount of space between the back of a long graphics card and the DIMM latches to ease the replacement of memory with a graphics card installed. Increasing that space could have been accomplished by moving the RAM towards the motherboard's upper edge, shown on the right in this photo.

The lower PCI Express slot is a different matter; behind it are four SATA connectors, two of which (the red ones) may be blocked by graphics card coolers on long cards such as highest-end or workstation graphics models. Long cards would further block access to the blue ATA/100 connector, except that it has been turned 90 degrees. But turning the connector in this direction may also cause it to be blocked by parts of the case once the board has been installed.

One place Asus stands out is by making use of all seven possible slot positions, where competing solutions typically use five or six. Asus accomplished this without crowding the DIMM slots, by putting a PCI Express x1 slot above the uppermost x16 slot (see the small white connector next to the blue PCI Express x16 slot). Typical PCIe x1 cards include TV tuners and storage interface adapters, which are usually short enough to avoid crowding DIMM latches.

Preferred positioning for major power connectors is the top edge, but putting both the ATX and ATX12V leads at the top edge is less than ideal for distributing power to various motherboard components. Some solutions place power connectors behind the sound ports, where the cable will cross the CPU cooler, probably hindering airflow. Asus' solution is better than most, but it still requires dragging the large extended ATX cable past several drives in the case, which could make cable installation more difficult.

Parallel ATA connectors should always be placed above the midpoint of the board to ease cable routing for optical drives (these are typically located in the top part of tower cases for easy access). Asus' middle-mounted (blue) ATA/100 connector isn't too far out of reach, but it still may have the clearance problems mentioned above.

Serial ATA cables should be mounted below the midpoint of the board, because most cases have the hard drive cage at the bottom. Asus' selection would have been fine, if not for interference issues with the lower PCI Express x16 slot when using long graphics cards.

The ideal location for front-panel audio connections is behind the rear-panel audio jacks, to ease cable routing for mid-mounted or top-mounted front panel ports. Because this portion of the board is usually crowded, the area in front of the slots becomes an acceptable location for front-panel USB and IEEE1394/Firewire connectors. Front panel connections should never be mounted in the lower rear corner of the board, as many cases use cables that simply won't reach that far. Asus placed its front-panel audio header behind the fifth and sixth slots, and IEEE1394 ports along the bottom edge. Both locations can hamper cable installation.

A final layout consideration is fan connector number and placement. Asus offers the perfect minimum configuration, its CPU fan connector near the DIMM slots, exhaust fan header near the audio ports, intake fan connector in the front lower corner and another fan connector near the Northbridge. Two exhaust fan headers would be preferred.

Admittedly, we are critical of layout and positioning issues, but our goal is to indicate possible problems, not to rate this particular board. It may still be a great choice for you as long as the issues mentioned here do not interfere with your requirements.