|If you are using a two four pin molex to 6 pin adapter, you must make sure that you use the connector on two 4 pin molex connectors on two different wire runs or you will not be dividing the load evenly on multiple 12volt rails since on most cheaper power supplies with multiple 12 volt rails cannot handle the graphics card on a single rail.|
If you reconnect the onboard graphics (remove the graphics card if needed) and go into your BIOS set up see what option you have as far as graphics set up is concerned. You would be best if there is a setting "use onboard graphics if no other graphics cards are present" (or similar), if there is, then use it. If there is an option for graphics source then you might have a drop down with options like PCI, PCIe 16x, and possibly others, use PCIe 16x or PCIe if that is an option (if ther are multiple PCIe options, choose the one with the highest multiplier and the first of them where applicable). If you are confused by it post the options back for further advice.
You have to be a little bit crazy to keep you from going insane.