Asus P8B-MX - Manual (Page 52)

2-34 Chapter 2: Hardware information
11. ATX power connectors (24-pin ATXPWR1, 8-pin ATX12V1)
These connectors are for the ATX power supply plugs. The power supply
plugs are designed to fit these connectors in only one orientation. Find the
proper orientation and push down firmly until the connectors completely fit.
• DO NOT forget to connect the 24+8-pin power plugs. Otherwise, the system
will not boot up.
• We recommend that you use a PSU with a higher power output when
configuring a system with more power-consuming devices. The system may
become unstable or may not boot up if the power is inadequate.
• This motherboard supports ATX2.0 PSU or later version.
• Ensure that your power supply unit (PSU) can provide at least the minimum
power required by your system.