Motherboard form-factor used by “branded” PCs like Compaq. This form factor replaces the old LPX form factor and it is based on ATX form factor. As it happens with LPX, NLX motherboards don’t have slots. The slots are located in a separated board, called backplane, where the motherboard is plugged. The idea is to allow the design of thin PCs, since on this kind of motherboard the expansion boards aren’t perpendicular to the motherboard but parallel.
NLX motherboards measure 8 to 9” x 10 to 13.5” (20.3 to 22.9 cm x 25.4 to 34.5 cm).
Visually speaking it is easy to differentiate an LPX from an NLX motherboard. On LPX form factor the backplane connector is located in the middle of the motherboard and this connector looks like an expansion slot (female connector). On NLX form factor the backplane connector is located on one of the motherboard edges and it is a 340-pin edge contact male connector, similar the one used by expansion boards.

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Figure 1: NLX motherboard.

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Figure 2: Backplane with expansion slots, this is where the motherboard is connected.

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Figure 3: NLX motherboard installed on its backplane.