Re: $3000 budget building.
I don't know if you mean $3000 American or Canadian or whatnot, but you don't need that much to build an awesome gaming computer. First, I would advise you to decide if you want to spend all $3000, or save money if you think you are safisfied with a good Gaming Computer (and in most cases, it's pointless to build the "Best" gaming computer).
These are 2 Specs that I recommend:
First, Decent and Money Saving Option.
CPU: Intel Dual core 3.0GHz speed and up.
RAM: DDR3 SDRAM with 1333MHz speed and 6GB space (get more speed and space if you want to, but that would pretty much be enough).
GPU: Nvidia GTX 285, GTX 295, ATI Radeon HD 4870 and Dual HD 4870.
HDD: 7200 RPM Conventional SSD however amount of space you would like.
Power: You would need sufficient amount of Power Outlet so around 800-850 Watt range.
Cooler: Standard Air Cooler or Liquid Cooling for more cash.
Second, Pure Performance.
CPU: Intel i7 Quad core processor with 3.0 GHz speed (approx $500 more than the previous option with Dual cores).
RAM: 1333MHz, 1600MHz or higher DDR3 SDRAM with 6-8GB memory.
GPU: Dual GTX 285, Dual GTX 295 and Dual HD 4870 Crossfire.
HDD: 10000 RPM conventional HDD or 256GB or 512GB SSD (if the budget allows)
Power: You would need sufficient amount of Power Outlet so around 950-1100 Watt range.
Cooling: Liquid Cooling.
You should choose this options at Gaming Computer Brands such as Ava Direct, Cyberpower or iBuyPower for good Price-to-Performance ratios.