Asus P5L-MX - Manual (Page 22)

1-10 Chapter 1: Product introduction
The CPU fits in only one correct orientation. DO NOT force the CPU
into the socket to prevent bending the connectors on the socket and
damaging the CPU!
6. Close the load plate (A), then
push the load lever (B) until it
snaps into the retention tab.
A
B
The motherboard supports Intel ® LGA775 processors with the Intel ®
Enhanced Memory 64 Technology (EM64T), Enhanced Intel SpeedStep ®
Technology (EIST), and Hyper-Threading Technology.
If you install a dual-core CPU, make sure to connect the chassis fan cable
to CHA_FAN connector for system stability.