What is PCIe x16 Slot

1 x PCIe x16 slot 1 x PCIe x1 slot

There's been talk that some PCIe slots on new motherboards will (The support may only be extended to ordinary PCIe x16 expansion slots

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can you have a higher flush in poker 1 PCIe x16 slot; 4 SATA3, 2 x ; Graphics Output Options: HDMI & Display ; 1 Rear USB Gen2x2 Type-C, 1 Rear USB Gen2 Type-A