Dell OptiPlex 990 (Early 2011) - Manual (Page 56)

When the Insert key is pressed in the Manage Certificate Hash screen, the following screen is displayed.
To add a customized certificate hash: Type the hash name (up to 32 characters). When you press , you are
prompted to select the algorithm of hash being used for PKI provisioning. Type Y if SHA1 is being used, otherwise enter N.
The supported hash algorithms are:
1. SHA1
2. SHA2-256