if you are gonna overclock go with either the extreme6, just overall better than the 4, or the Asus p8p67 pro. Both are around 200. Also where are you getting your parts, You can get a better deal on a PSU than the one you have listed depending on where you're getting the stuff from.
Also the 300 is pretty small, you might take that into consideration. the 570 is similarly sized to the card that's in this 300
Also the 300 is notorious for bad cable management which will cut temps and won't look as pretty.
Other than those suggestions, looks good!
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