Custom Riser Card for MB770 Platform

MB770 motherboard is only PCI 2.1 compliant and therefore doesn't provide 3.3VSB (3.3 V stand-by voltage) on pin A14 of the PCI bus connector. This voltage is is supplied to the core of CM2 and is used to turn the main power on/off. Furthermore, even the wake-on LAN (WOL) connector on the motherboard doesn't provide stand-by voltage (and on most motherboards the WOL connector is not even installed).

One solution to this problem was to create a custom riser card shown in figure 1 which has a separate feed for stand-by voltage directly from the power supply, voltage regulator for 5 to 3.3 V conversion, intercepts pin A14 between the two PCI connectors and feeds 3.3V to the CM2 card.

The assembled node with custom raiser and CM2 card is shown in Figure 3. The +5VSB clamp and feeder wire are pulled out of the box just to emphasize the setup.