Welcome to the forums, newcomer!
Model for your Thermaltake PSU? Also, no, you need to have the connector populated the right way. If it's an 8 pin, use an 8pin PCIe connector. You should not confuse the 8pin EPS to the 8pin PCIe as well. For your GPU, the PSU should almost always come with a PCIe connector which is 6+2 which is actually an 8pin PCIe.