"Processor-NB Frequency Multipl" ties the Northbridge clockspeed to the FSB with a multiplier. Overclocking option, probably best to leave at auto.
"C1E Support" is "CPU enhanced halt": a powersaving option in system halt state. When in halt state CPU frequency and voltage are reduced to save power.
Not familiar with the others.
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Processor Downcore
Secure Virtual Machine Mode
ACPI SRAT Table