ok... this thread went about the way i expected it to. Someone wants an AMD chip, and the forum spends the next 4 pages telling him an intel can do it better for cheaper (which is true sometimes) then pushes square pegs into round holes when the OP says he needs certain things an AMD can do well, which is why he wants one.
OP... understand Intel does produce far better chips then AMD for "single threaded" tasks. For the money, pound for pound, intel has the best gaming CPU out there (or pair of them depending on how you look at it). Now that this disclamer is out of the way.
all the 3d cad software running concurently, depending on how you're using it can be a beast on a high end multicore system. AMD certainly CAN play in that feild quite well. For the money this is the sweet point in the new FX chips price/performance frankly. Considering a new FX 8350/6300 will give you a responsive and excellent high end gaming experience (all be it a few frames slower then an intel chip) as well as blow a comparitive intel chip out of the water in the high end cad functions they make an excellent option for you.
So... since your goal is a "gaming capable" Cad number crunching chip an FX makes a lot of sense. So lets make it fit your budget.
CPU: AMD FX-6300 ($129.99 @ Amazon)
CPU Cooler: Cooler Master Hyper 212 EVO ($24.99 @ Newegg)
MB: Biostar TA970XE ($99.99 @ Amazon)
Memory: G.Skill Sniper 8GB ($34.98 @ Outlet PC)
SSD: Crucial M4 128GB ($99.99 @ B&H)
HD: Seagate Barracuda 2TB ($89.99 @ NCIX US)
GPU: Gigabyte Radeon HD 7870 ($229.99 @ Amazon)
Case: Cooler Master Elite 311 (Black) ATX Mid Tower Case w/420W Power Supply ($59.99 @ NCIX US)
Total: $769.91
That's inside your budget... and would be a great feature rich gaming pc as well. If you have a few dollars more laying around upgrading that CPU to an 8350 would show you stronger multitasking processing.