ASROCK X299 Extreme4 Mode D'emploi page 14

2.1 Installing the CPU
1. Before you insert the 2066-Pin CPU into the socket, please check if the PnP cap
is on the socket, if the CPU surface is unclean, or if there are any bent pins in the
socket. Do not force to insert the CPU into the socket if above situation is found.
Otherwise, the CPU will be seriously damaged.
2. Unplug all power cables before installing the CPU.
CAUTION:
Please note that X299 platform is only compatible with the LGA 2066 socket, which is
incompatible with the LGA 2011-3 socket (for X99 platform).
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