Asus RS520-E6/RS8 - Manual (Page 58)

4-14 Chapter 4: Motherboard information
11. SSI power connectors (24-pin ATXPWR1, 8-pin ATX12V1/2)
These connectors are for SSI 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.
• For a fully configured system, we recommend that you use an SSI
12 V-compliant power supply unit (PSU) for LGA1366-socket Intel® Xeon
processors.
• DO NOT forget to connect the 24+8+8-pin power plugs; otherwise, the
system will not boot up.
• Use of a PSU with a higher power output is recommended when configuring
a system with more power consuming devices. The system may become
unstable or may not boot up if the power is inadequate.
• You must install a PSU with a higher power rating if you intend to install
additional devices.