Do they require power for use and if so is there a power cable included?

Yes they need a power hook up to function. I recommend that you view some mining rig U2 tube videos to better understand the setup better.

Questions & Answers: ITHOO 6pcs/Lot 4 Solid Capacitors VER PCI Express PCI-e 1X to 16X Mining Riser Card Cable,USB 3.0 Bitcoin Miner Machine X16 to PCI e Mining ETH GPU Riser Adapter Power by SATA,Molex 4pin , 6pin

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ITHOO 6pcs/Lot 4 Solid Capacitors VER PCI Express PCI-e 1X to 16X Mining Riser Card Cable,USB 3.0 Bitcoin Miner Machine X16 to PCI e Mining ETH GPU Riser Adapter Power by SATA,Molex 4pin , 6pin

6Pack PCIe 1X to 16X Riser Card
Integrate Molex 4pin, SATA and 6-pin PCI-E interface on PCB
60CM USB 3.0 Cable
USB cable color of Red, Blue,Black or white will be sent randomly- Function is the same

$55^.39 –