Dell OptiPlex 990 (Early 2011) - Manual (Page 7)

computer with a desk-side visit in one of two ways:
The key can be manually typed into the MEBx.
The SCS can create a list of custom keys, and put them onto a specially formatted USB thumb drive. Then each AMT
computer retrieves a custom key from the specially formatted USB thumb drive during BIOS boot as detailed in the
Configuration Service section of this document.