Power supplied, really. Your motherboard ONLY allows for 75W of power to flow to the GPU via motherboard. Any more requires an external power supply connector - if you are using a prebuilt machine, included OEM power supplies are usually low wattage, restricting upgrade room without upgrading the PSU as well, and might not have PCIe connectors for the GPU. If you're getting a 1050ti that doesn't need external power, you will be fine.