You must invoke C6 package sleep state to use it. There is no impact too the user if this is turned off. However, it may provide a marginal power usage improvement if set.
Access the BIOS Setup utility (see To Access the BIOS Setup Utility in Sun Ultra 27 Workstation Service Manual).
Ensure that the BIOS is at v1.03 or later.
The BIOS version is listed under the Product Information menu in the BIOS Setup Utility.
Use the right or left arrow key to navigate to the Advanced menu screen.
Use the down arrow key to highlight Configure Advanced CPU Settings and press Enter.
The Configure Advanced CPU Setting submenu screen appears.
Use the down arrow key to highlight Package C-State Limit (under Intel(R) C-State Tech) and press Enter.
An Options popup window appears.
Highlight C6 and press Enter.
Save and exit the BIOS Setup Utility.
The workstation reboots.