Asus STRIX X99 Manual page 84

The following item appears only when you set the CPU Strap to [100MHz], [125MHz],
[167MHz], or [250MHz].
PLL Selection [Auto]
This item is set to LC PLL by default for better stability. Select SB PLL when BCLK
(base clock) frequency is far away from 100MHz. This may affect the functionality of
other devices which need precise clock jitters.
Configuration options: [Auto] [LC PLL] [SB PLL]
Filter PLL [Auto]
Set this item to high BCLK (base clock) mode when using a very high BCLK to improve
the overclocking capability.
Configuration options: [Auto] [Low BCLK mode] [High BCLK mode]
BCLK Frequency [100.0]
This item allows you to set the BCLK (base clock) frequency to enhance the system
performance. Use the <+> or <-> to adjust the value. The value ranges from 80.0MHz
to 300.0MHz.
We recommend you to set the value based on the CPU specification as high BCLK
frequencies may damage the CPU permanently.
Initial BCLK Frequency [Auto]
This item allows you to start overclocking the system from the initial BCLK (base clock)
frequency to the assigned BCLK frequency. Use the <+> or <-> to adjust the value.
The value ranges depend on the value you set on BCLK frequency.
ASUS MultiCore Enhancement [Auto]
[Auto]
[Disabled]
CPU Core Ratio [Sync All Cores]
This item allows you to set the CPU core ratio limit per core or synchronize automatically to
all cores.
Configuration options: [Auto] [Sync All Cores] [Per Core]
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Source Clock Tuner [Auto]
This item allows you to select the source clock based on the assigned CPU
strap for a better overclocking capability.
Configuration options: [Auto] [8Ohm dbl] [7Ohm dbl] [6Ohm dbl]
[5Ohm dbl] [4Ohm dbl] [3Ohm dbl] [2Ohm dbl]
This item allows you to apply ASUS optimized core ratio settings when
oveclocking.
This item allows you to apply the default core ratio settings.
Chapter 3: BIOS Setup