Your power supply is too underpowered, in my opinion I would run a 750 or 800, but then again I like having the room to expand.
Bear in mind when you run things at the bare minimum you get the bare minimum results, also you have to account for everything as a whole, not just the GPU, but the CPU, your case fans, RAM, EVERYTHING uses power.
When you get home, take a picture of the setup and we can likely guide you to any misconfigurations and make better recomendations.
Based off the info you have provided though, you will likely need more power
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