IBM Power System 9008-22L Manual page 30

See Figure 11 on page 16 for the location of the adapter latch.
(L007)
CAUTION: A hot surface nearby. (L007)
Attention: Before you insert the adapter in the PCIe slot, ensure that the adapter has nothing
attached to it.
6. Press the adapter firmly into its connector ensuring that it is seated.
See Figure 11 on page 16.
7. To lock the adapter in its slot, rotate the adapter latch (B) in the direction that is shown.
Figure 11. Installing or replacing a PCIe adapter in a 9008-22L, 9009-22A, or 9223-22H
16 Power Systems: PCIe adapters for the 9008-22L, 9009-22A, or 9223-22H