PCIe expansion cards are some of the most powerful, not to mention affordable, upgrades you can make to a PC. The PCIe bus offers a high-bandwidth connection to the system, and the versatility of the various PCIe sockets is a boon for power users hoping to expand the capabilities of their build. If you have one or more PCIe cards installed on your motherboard, it’s possible that they are only running at half their maximum speed. Due to the motherboard design and PCIe lane sharing, your expansion card could be running in x2 instead of x4 mode (or x4 instead of x8). Not all motherboard PCIe slots are wired with the same number of PCIe lanes, so picking the wrong slot can easily throttle your PCIe card. It’s possible to check whether this is indeed happening in your system, and swapping slots can often fix the problem.