MSI ATX BX1 User Manual page 20

Step 3: Install the Heat Sink to the Processor.
Push down the plastic clips, so that they are in line with the hole on
the processor. check for perfect fit.
Step 4: Insert the Processor in
Insert the Processor like inserting a PCI or an ISA card.
Step 5: Lock the Procesoor
Lock the processor by putting the Retention Cap provided.
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