HP J Class Owner's Manual page 175

Processors are shipped with a dust cover (A) over the connector.
There are two connectors on the CPU board for processors. If one
of these connectors is not being used, it will have a dust cover (B)
over the connector.
To remove these dust covers, follow the steps in Figure A–28.
Figure A–28. Removing CPU and Connector Dust Covers
B-47