This is my first gaming PC, although I bought it prebuilt and have only been tinkering with it. My GTX 970's fans spin and its lights turn on, but the computer doesn't detect the card and I get no picture when connecting HDMI to the graphics card. The card has one 6-pin power socket, while my power supply cables are 8-pin connectors. I'm not sure whether they are compatible or whether I'm connecting something incorrectly. Connecting the monitor to the motherboard produces a display, but connecting it to the GPU gives me a black screen. Is there anything I can try before assuming the graphics card has failed?
4 Answers
Make sure the monitor cable is connected to the graphics card, not the motherboard, once the GPU is installed. Also reseat the card in the PCIe slot and check that the PCIe power connector is fully inserted. Listing the exact motherboard, power supply, and graphics card models would help diagnose it further.
Fans and LEDs only show that the card is receiving some power; they do not prove that the GPU is functioning. If the correct PCIe cable is connected, the card is seated properly, and the system still does not detect it, try another PCIe slot or test the card in another computer. It may have failed, especially if it is an older used card.
The most likely issue is either using the wrong type of power cable or not having the card fully powered. A PCIe 6+2 cable is appropriate for a 6-pin GPU socket, while a CPU 4+4 cable is not. If the correct cable and a reseat do not help, the card itself could be defective even though its fans spin and lights work.
Check whether those 8-pin cables are actually PCIe power cables that split into 6+2. You can slide off the extra two-pin section and plug the 6-pin portion into the graphics card. Do not use an EPS/CPU cable that splits into 4+4, since that is wired differently and is not for the GPU.
I tried connecting the 6-pin portion to the graphics card, but it still gives me a black screen.
The motherboard output works, but the GPU output stays black. After connecting the 6-pin cable, neither output displayed anything.