On the PCIe PLL Bandwidth Tester Windows application that's used with the CR286A, there is a drop down under "Options" called "Enhanced Measurement" and has the options of "Standard", "Sensitive", and "Disabled".What does each option do?

In 8G mode only, some DUT’s are sensitive to the initialization routine, which involves forcing a re-lock of the DUT PLL several times to optimize the peaking measurement.

• The “Standard” selection uses a method that toggles the CR divider reset to cause the relock.
• The “Sensitive” selection uses a method that changes the frequency to cause the relock.
• The “Disabled” selection disables enhanced measurement.

The default is “Standard”, and in almost all cases it works just fine.  In rare cases, the DUT PLL will have difficulty with the resulting clock shift, and in those cases you may have more success using the “Sensitive” mode.  Disabling the enhanced mode is not recommended, although any changes to the measurements should be small.