I am a beginner builder trying to learn, and have a PC with an ASUS Sabertooth X58 LGA 1366 Intel X58 SATA 6Gb/s USB 3.0 ATX Intel Motherboard with the two tan-colored PCI 2.0 x16 slots already in use; so I'd like to know if the Koutech System Dual Channel SuperSpeed USB 3.0 PCI Express (x1) Card (2x internal) that requires a one-lane (x1) PCI Express 2.0 slot will work at the maximum speed if placed in the black-colored PCIe x16 (at x4 mode) on the motherboard.
The Koutech web site for this card says: "To achieve the maximum throughput, the PCI-Express slot must be version 2.0 or higher. Performance per port may decrease if both ports are transferring data simultaneously due to limited throughput of the PCI-Express slot.", so I'd like to be sure it will work at max throughput in the black-colored PCIe x16 (at x4 mode) on the motherboard. So I guess the basic question is if the Asus Sabertooth x58 motherboard black-colored PCIe slot is PCIe v1.0 front-side bus or 2.0 front-side bus.
I haven't been able to figure out from the Asus or Koutech web sites if that would work, and I've tried to understand the PCI language/nomenclature, but haven't quite got it figured out yet (e.g., from Wikipedia and Directron web sites).
You can safely install a PCIe x1 card in any of the PCIe x1, x4, x8, and x16 slots and use it at full speed because you say the slot already runs at x4. Actually, what you need is 1x. If you think you have two USB 3 ports and you need 2x, that is not true. You still need 1x. You divide data throughput between the ports if two ports are active ( transmitting data ) at the same time.
My plan is to get the USB3 PCIe card (Koutech Dual Channel SuperSpeed USB 3.0 PCI Express Card (2x internal) Model IO-PEU232) with a cable (StarTech 3 ft. SuperSpeed USB 3.0 Cable A to B Model USB3SAB3)
to connect to a USB3 front panel hub (Koutech IO-FPH430 4-Port SuperSpeed USB 3.0 Front Panel Hub in the 3.5" slot on a Lian Li PC-A05 mini-Tower case so I can have USB3 on the front of the PC to use for USB3 external back up drives. I'll plan to plug the PCIe card into the available black-colored PCIe x16 (at x4 mode) on the motherboard.