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).

Custom CM2 Riser Card

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 and feeds 3.3V to the CM2 card on PCI connector A14.

Standby voltage feed

Self-tapping connector CM2 stand-by voltage is provided with the separate wire that is attached directly to the +5VSB wire of the ATX power supply with the self-tapping connector (MOLEX Multi-Lock Insulation Displacement Connector (IDC) ) show on figure 2.

The purple wire on the ATX power supply connector is fed through the slit opening on the IDC while the red wire from the riser card is fed into the second hole on the clip and the taping header is gently squeezed into position and locked with the cover ATX-20 Pin Male (cable) Connector Pin Layout

Pin Name Color Description
1 3.3V Orange +3.3 VDC
2 3.3V Orange +3.3 VDC
3 COM Black Ground
4 5V Red +5 VDC
5 COM Black Ground
6 5V Red +5 VDC
7 COM Black Ground
8 PWR_OK Gray Power Ok (+5V & +3.3V is ok)
9 5VSB Purple +5 VDC Standby Voltage (max 10mA)
10 12V Yellow +12 VDC
11 3.3V Orange +3.3 VDC
12 -12V Blue -12 VDC
13 COM Black Ground
14 /PS_ON Green Power Supply On (active low)
15 COM Black Ground
16 COM Black Ground
17 COM Black Ground
18 -5V White -5 VDC
19 5V Red +5 VDC
20 5V Red +5 VDC
20 Pin ATX Connector

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. ORBIT node (V2) with custom riser card and CM2 installed

Last modified 9 years ago Last modified on Jan 11, 2013, 1:28:13 AM

Attachments (4)

  • CM2-Riser.jpg (31.1 KB ) - added by seskar 13 years ago. Custom CM2 Riser Card
  • Node-with-CM2.jpg (136.8 KB ) - added by seskar 13 years ago. ORBIT node (V2) with custom riser card and CM2 installed
  • Clip.jpg (37.0 KB ) - added by seskar 13 years ago. Self-tapping connector
  • ATX20-Male.png (579 bytes ) - added by seskar 13 years ago. ATX-20 Pin Male (cable) Connector Pin Layout

Download all attachments as: .zip

Note: See TracWiki for help on using the wiki.