PCIe x4 and x8 cards can draw up to 25W from the motherboard's slot, while x1 cards are limited to 10W unless configured as a 'full-height' or 'high-power card' to pull the aforementioned 25W.
The Altera ® devices can also deliver up to 80 Gbps on 15 m of copper cable on a new cable specified by PCI-SIG ... and the corresponding test-bench and reference designs for x1, x2, x4 and x8 ...