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First it will depend on the Mac you have and if it is worth upgrading. Personally I would be looking at a gaming PC. Most older Mac's are going to be to expensive to upgrade or darn near impossible to upgrade with things like RAM being soldered in or sealed shut like the iMac. Seriously I would consider looking at a new PC over trying to upgrade a Mac. Probably cheaper in the long run.
Here are the minimum requirements:
- Intel Core i7-6700HK Processor
- Nvidia GeForce GTX 980 GPU
- 8 GB RAM - Two USB 3.0 Ports
- HDMI 1.4 - 1920 x 1080 Display
- Windows 7 or Above