RadiSys PL35Q, Руководство по эксплуатации продукта, Страница: 28 / 72

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Hardware Reference
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Video
The GMCH provides an integrated graphics device (IGD) delivering cost-competitive 3D, 2D
and video capabilities. The GMCH contains an extensive set of instructions for 3D operations,
2D operations, motion compensation, overlay, and display control. The GMCH‘s video engines
support video conferencing and other video applications.
The GMCH also has the capability to support external graphics accelerators via the PCI Express
graphics (PEG) port but cannot work concurrently with the integrated graphics device. However,
the dual independent display can work via the ADD2/Media Expansion Card attachment.
High bandwidth access to data is provided through the system memory port.
System memory allocation
The GMCH uses a UMA configuration with DVMT for graphics memory. When the onboard
video controller is not used, it is recommended to disable it via the BIOS setup utility to prevent
unnecessary system memory allocation.
By default, the system BIOS allocates 8MB of system memory to the video controller to support
legacy VGA displays. The amount of system memory reported by the BIOS will reflect this
reduction when the onboard video controller is enabled. Once the operating system loads, the
video driver dynamically allocates further system memory depending on availability and the
application requirement. Systems should have at least 256MB of system memory when using
these graphics drivers.
PCI Express graphics
The Q35 motherboards support PCI Express graphics acceleration cards via the PCI Express x16
graphics slots. This support includes:
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One PCI Express x16 graphics slot on the PL35Q motherboard, electrically x16 interface
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PCI Express frequency of 1.25 GHz resulting in 2.5 Gb/s each direction per lane
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Raw bit-rate of 2.5Gb/s on each lane while employing 8b/10b encoding to transmit data
across the interface.
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Maximum theoretical bandwidth of 4GB/s in each direction simultaneously, for an
aggregate bandwidth of 8GB/s when using 16 lanes.
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ADD2/media expansion cards support with capabilities of dual independent displays with
the integrated graphics devices.
Note: The PLVDS03-0-0 motherboard does not support this functionality, since the SDVO
channel is tied to the onboard DVI controller. If MEC cards are required in your application,
use the entry-level PLV03-0-0 motherboard, which has the DVI controller depopulated.