Pins are arranged in two rows. The (1, 3, 5, 7...) is closer to the center of the motherboard, while the even-numbered row (2, 4, 6, 8...) is closer to the motherboard's edge.
A major part of the "full story" is the Front Panel USB/Audio/Card Reader assembly. On many Acer Aspire cases, the front panel buttons were not separate wires. They were integrated into a PCB that also housed the USB ports and card reader. acer ipisb-vr rev 1.01 front panel
Here is the full story behind the motherboard, specifically focusing on the infamous Front Panel connection issue. Pins are arranged in two rows