Should I Use Two Pcie Cables For GPU?
Generally speaking, it's okay to only use one PCIe power cable between your Power Supply unit and your graphics card. However, there are a few situations in which this is less than ideal.
The most obvious case in which this isn't OK is if your graphics card requires a dual 6-pin or 8-pin power connector. These are rated for 150W each which, when combined with 75W from the PCIe slot, means that your graphics card can draw up to 300W in total. Most mid-range to high-end graphics cards will require either dual 6-pin or dual 8-pin power connectors. You might see some newer ones with an additional 12+4-pin connector for those who want to tinker around with their overclocking (these are reserved for the most power-hungry of graphics cards).
In those cases, it's recommended that you use two separate PCIe cables rather than a single pigtailed cable. This is because the wires in a dual 8-pin cable are rated for double the amount of current than a single one. This will ensure that your graphics card is receiving enough power during peak performance and reduce the chance of a Coil Whine failure which can ruin your gaming experience. This also helps prevent overheating damage to the graphics card and the PSU's power cables which is a common cause of power supplies melting, burning out, or simply not working properly. This is a particular issue in cheap power supplies which often don't have high-quality power cables.