|Do you not know your own system specs? There's a lot of info missing in the above list & a lot listed that's useless.|
CPU: FX-6100 - http://www.cpu-world.com/CPUs/Bulld...
Motherboard: Gigabyte GA-78LMT-S2 - http://www.gigabyte.com/products/pr...
RAM: 4GB (no speed or configuration provided)
Graphics: not listed
HDD: not listed
Power Supply: not listed
Since you have an FX-series CPU & want best performance, the motherboard should be replaced with a board based on an AMD 900 series chipset combo such as the 970/SB950 or 990FX/SB950.
Optimal RAM for an FX-series CPU is DDR3-1866 (or better).
Graphics? If you're still using the integrated Radeon HD 3000, it's time to upgrade to an actual graphics card. Which card to get would depend on how much you're willing to spend & what the primary use will be. You don't need a gaming card for media.