So I'm thinking about buying a new gpu. It needs an 8 pin cable which I have. The cable is currently connected to motherboard probably to power the pci e. Do I need 2 8 pin cables or I can use the one I have connected to the motherboard on the gpu?
Your Motherboard uses an 8 pin for the CPU power...That stays there can't be used to power GPU's.
You need a 6+2 = 8 pin PCIE\VGA cable to run the graphics card.
Someone please correct me if I'm wrong, but the 8 pin currently connected to the motherboard is probably for the cpu power. And you would need a separate dedicated 8 pin pcie connector for your gpu.
Your Motherboard uses an 8 pin for the CPU power...That stays there can't be used to power GPU's.
You need a 6+2 = 8 pin PCIE\VGA cable to run the graphics card.