Okay guys, so i have a 500 watt PSU with no 6 pin connector. I've established that I need a 6pin molex connector. The one I have used two molex end connectors but I only have one free'd up on my PC. Would it be okay to just use one of them and tie the other one off?
If it's a quality one, you'd likely be fine. If it's a junk PSU that's not really a modern 500 watt, either because of a beefy +5v rail or simply outright lying (which is common) then you still may be OK -- a GTX 650 doesn't use much power -- but it's riskier. Would need more information about your PSU to say for sure.
Generally you want to use both of the molex connectors, the reason is that there is a huge amount of power being sent to the video card over these wires, and the wires are small. Spreading out the power over multiple wires will ensure things like the wires melting won't happen. It's best if the two molex connectors you use are are on different wires coming from the power supply.
Even better would be to replace the PSU with a supply that's designed for modern computers.
Get a Corsair CX500 since it is available in many areas in case of geographical limitations. This should have been a what new power supply should I get question instead of running the GTX 650 off of just one MOLEX on the PCI-E adapter.