C6 is a CPU power saving mode that can, under some circumstances, cause spontaneous reboots on MWG 5000-B and 5500-B (Intel based) appliances.
It is a very rare race condition that can lead to this behavior and it is recommended that you follow the steps below only after McAfee technical support has validated that you experienced this exact condition and advised to follow the remediation steps in this article.
Note that there is no performance impact expected from this change. Disabling C6 simply prevents the CPU cores from going into this sleep mode.
Disabling C6 mode
** The appliance will need to be taken offline during this procedure as changes have to be made to the BIOS **
1. Connect to the console either through RMM (see setup instructions here: https://community.mcafee.com/docs/DOC-4832) or through physically attaching a keyboard and monitor.
2. Reboot the appliance and make sure that you catch the prompt to "Press F2 to enter setup"
3. In the BIOS, use the "right arrow" key to move to the "Advanced" tab
4. Press "Enter" to select "Processor Configuration" and then use the "down arrow" to find the option for "Processor C6"
5. Hit "Enter" to open the options for "Processor C6" and use the "up arrow' to switch to "Disabled". Then hit "Enter" again.
6. Press "F10" to "Save and Exit". Confirm with "Yes".
7. The appliance will now reboot again and start your Web Gateway Services back up.