MSI WindBOX III Plus Manual page 46

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BIOS Setup
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DVMT Total Gfx Mem
This setting specifies the memory size for DVMT.
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Primary IGFX Boot Display
Use the field to select the video device which will be activated during POST.
This setting has no effect if external graphics are present. Secondary boot
display selection will appear based on your selection. VGA modes will be
supported only on primary display.
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