Hello Everyone, I am new on mac and consider to buy iMac 21.5' and I have a question about graphic card. You can find the properties that i am looking for. 3.1GHz Quad-core Intel Core i7, Turbo Boost up to 3.9GHz 16GB 1600MHz DDR3 SDRAM - 2x8GB 1TB Fusion Drive NVIDIA GeForce GT 650M 512MB GDDR5 I am an engineer and i need to used Autocad and revit structure without problem. Do you think that 512MB will provide smooth usage for me? because Apple doesn't provide any upgrade for graphic for for 21.5 Macs. Thanks and Have a good weekend.