Nvidia IN9 32X - Manual (Page 19)

Hardware Setup
IN9 32X/IN9 32X-MAX 1-13
1.7.3 PCI Express X16 Add-on Slots (Install Graphics Card)
These slots support the connections of graphics cards that comply with PCI Express
specifications. This motherboard provides triple PCI-Express X16 slots:
One PCIE graphics card installation (Normal Mode):
Insert your PCIE graphics card into [PCIEXP1] (MASTER) slot.
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The [PCIEXP3] slot supports up to X8 bandwidth only.