Up the wattage on your PSU.
Upgrade your CPU to maybe a 6300 or 8320.
Throw out the liquid cooling (completely unneeded for your CPU and budget), switch it for something like a Hyper 212.
Reduce your RAM latency to 1600 MHz (1866 gives next to no performance benefit while being pricier).
Upgrade your GPU to something like a 7850 or 660.
Trash the OS and be a pirate and get a cracked version.
You should be able to get everything I mentioned for around your budget.
Just shoot me a quote or VM if you have any other questions.