This is just another way to go with things. I swapped the power supply for a better quality unit. For about the same price a dual channel ram kit may provide a bit better performance but there's not a huge difference between single and dual channel ram. It is a bit faster than the ram you'd selected though. The z97 makes sense if you want to move to an unlocked i5 after awhile so you're set up for it. The wd green is a great drive as cheap bulk storage but being a green drive, it's slow to save energy. Painfully slow for a main system drive, it's more or less a low power option for storing bulk files you don't use often. Upgraded it to a wd blue which is a faster 7200rpm drive instead of the 5400rpm green. The i3 you picked was pretty expensive for an i3, just shy of a locked i5 and since you're looking to upgrade saving some on the i3 now would make more sense. The one I added is only slightly slower, 3.6ghz instead of 3.8 for about $40 less. The video card is up to you, some people are amd/ati fans, others prefer nvidia. The 280x is a little faster than the gtx 960 but it's a little more expensive. Nothing wrong with the 960 if you'd rather stick with that for now. Unfortunately any major boost to a 290/290x or gtx 970 is going to push the price way up.
I looked at some reviews for the r9 380's that just came out and they're having some issues. The 390's are exhibiting weird blackouts and the min fps on the 380's are lower than the existing 280/280x in a lot of cases. Maybe it's just driver problems (there's driver issues between current 280 and new 380) so rather than suggest a headache without knowing if/when it will sort itself out, may be best to stick with tried and true cards for now.
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel Core i3-4160 3.6GHz Dual-Core Processor ($108.99 @ NCIX US)
Motherboard: Asus Z97-A ATX LGA1150 Motherboard ($139.99 @ B&H)
Memory: G.Skill Ripjaws X Series 8GB (2 x 4GB) DDR3-1866 Memory ($52.99 @ Newegg)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($52.46 @ Amazon)
Video Card: XFX Radeon R9 280X 3GB Black Edition Double Dissipation Video Card ($235.99 @ SuperBiiz)
Case: Fractal Design Define R4 (Black Pearl) ATX Mid Tower Case ($74.99 @ NCIX US)
Power Supply: EVGA 750W 80+ Bronze Certified Semi-Modular ATX Power Supply ($54.99 @ NCIX US)
Operating System: Microsoft Windows 7 Home Premium SP1 OEM (64-bit) ($85.75 @ OutletPC)
Total: $806.15
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-06-18 15:44 EDT-0400