For gaming, you can change the GPU to a 750Ti. It's about $10 more than the one you have currently but is able to output any game on high at 1080p60fps.
If you want 3D rendering capabilities... how experienced are you? With that budget you may be pushing it if you're doing serious rendering work but the below might work for you.
PCPartPicker part list / Price breakdown by merchant
| Type | Item | Price |
|---|---|---|
| CPU | Intel Core i5-4590 3.3GHz Quad-Core Processor | $243.25 @ shopRBC |
| Motherboard | Asus H87M-PRO Micro ATX LGA1150 Motherboard | $79.98 @ Newegg Canada |
| Memory | G.Skill Ripjaws X Series 16GB (2 x 8GB) DDR3-1600 Memory | $139.63 @ DirectCanada |
| Storage | Seagate Barracuda 500GB 3.5" 7200RPM Internal Hard Drive | $55.98 @ DirectCanada |
| Video Card | MSI GeForce GTX 970 4GB Twin Frozr V Video Card | $438.95 @ Vuugo |
| Case | Thermaltake VL80001W2Z ATX Mid Tower Case | $46.50 @ Vuugo |
| Power Supply | EVGA 430W 80+ Certified ATX Power Supply | $35.99 @ NCIX |
| Optical Drive | Lite-On iHAS124-14 DVD/CD Writer | $19.10 @ Vuugo |
| Operating System | Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit) | $108.98 @ DirectCanada |
| Keyboard | Microsoft Keyboard 200 Wired Standard Keyboard | $20.98 @ Newegg Canada |
| Mouse | Microsoft JUD-00001 Wired Optical Mouse | $8.16 @ DirectCanada |
| Other | XBone Controller | |
| Prices include shipping, taxes, rebates, and discounts | ||
| Total (before mail-in rebates) | $1252.50 | |
| Mail-in rebates | -$55.00 | |
| Total | $1197.50 | |
| Generated by PCPartPicker 2015-04-07 17:18 EDT-0400 |