I've only plugged the 12vhpwr connector on the graphics card side in once. I'm selling it because the color doesn't match my graphics card. I believe you must plug in all four connectors on the PSU's 8-pin side. 16 Pin Micro-Fit to 4x8 Pin PCI-E 12VHPWR 600W Cable for NVIDIA 4000 Series (GPU) + CableMod Pro (cable organizer): 3x Aluminium/Black + Cable Shroud: Plastic/White Length: 600 mm Compatible with CORSAIR power supplies (Type-4 connector), some CoolerMaster power supplies, and Thermaltake power supplies. It cannot be used with CoolerMaster power supplies that correspond to the 12VHPWR Adapter Cable Type 1 (e.g., V Gold V2 / V Platinum / V SFX Gold / M2000 Platinum). Even with the same shape, it cannot be used with power supplies where the 8-pin latch side is 12V specification. Please use it with power supplies where the latch side is GND specification.