© National Instruments
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PXIe-8840 User Manual
To achieve maximum possible Turbo Boost frequencies, also enable the C-States setting.
When the BIOS is configured to boot LabVIEW Real-time, Turbo Boost is disabled
automatically. To manually enable Turbo Boost performance when in LabVIEW Real-Time
mode, refer to the
LabVIEW RT Configuration Overrides Submenu
.
•
C-States
—This setting enables or disables CPU power management. The default value is
Enabled
. Enabling C-States allows the processor to put idle CPU cores to sleep, allowing
active cores to run at higher than base frequencies when Turbo Boost is enabled. Enabling
C-States can increase application jitter, so be careful when enabling this setting on a Real
Time system. When the BIOS is configured to boot LabVIEW Real-time, C-States is
disabled automatically. To manually enable C-States when in LabVIEW Real-Time mode,
refer to the
LabVIEW RT Configuration Overrides Submenu
.
•
Hardware Prefetcher
—This setting enables or disables CPU cache hardware prefetching.
The default value is
Disabled
when booting LabVIEW Real-Time, enabled when booting
other OSs. Enabling hardware prefetching can increase system performance for some
applications, but can cause control algorithms to behave less deterministically.
•
Adjacent Cache Line Prefetch
—This setting enables or disables prefetching of adjacent
cache lines from memory to the CPU cache. The default value is
Disabled
when booting
LabVIEW Real-Time, enabled when booting other OSs. Enabling adjacent cache line
prefetching can increase system performance for some applications, but can cause control
algorithms to behave less deterministically.
Video Configuration Submenu
Use this submenu to apply alternate settings to the video configuration. Normally, you do not
need to modify these settings, as the factory default settings provide the most compatible and
optimal configuration possible.
•
Primary Display
—This setting specifies which video adapter the BIOS should use as the
primary adapter if more than one is present. To use an external video adapter as the primary
graphics adapter, choose
Add-in Board Video
. The default value is
Onboard Video
.
Power/Wake Configuration Submenu
Use this submenu to apply alternate configurations to the power and wake features of the chipset
and controller. Normally, you do not need to modify these settings, as the factory default settings
provide the most compatible and optimal configuration possible.
•
Restore After Power Loss
—This setting specifies the power state that the controller
should return to after AC power is lost. Valid values are
Stay Off
and
Turn On
. The default
is
Stay Off
. When set to
Stay Off
, the controller returns to the soft off power state after AC
power is restored. When set to
Turn On
, the controller powers on when AC power is
restored.
•
Power Button Off Behavior
—This setting specifies how the PXI Express power button
should behave. Valid options are
Normal
and
Disabled
. The default value is
Normal
.
When set to
Normal
, the OS controls the power button. When set to
Disabled
, pressing the
power button has no effect. The
Disabled
option should only be used in conjunction with
the PXI Express chassis’ inhibit mode switch.
