I think im getting the 640m because the big difference between 640m and 650m is the fps on low resolutions.
At high and ultra the differences are around 5-10fps
At lower fps .. even this 5-10 fps gain or lost makes the difference between playable and unplayable.
So, even for casual gaming i honestly believe 650M is a lot wiser choice than 640M. FusionDrive or SSD HDD will never be able to have any impact on gaming FPS.
I personally have went full Circle deciding what to get. I currently got 2010 13" macBookPro and wanted to get a iMac. was a bit disappointed with the 2012 iMac when it got released. Price Hike was one of the reason. Everything is at least 1.3x expensive in my country (India). I work with Photo/Video editing and graphics 2D/3D. And I do some Gaming ( only Simulation of car, Plane, Space genre).
So, I went to look out for building a windows PC and for the same price of a entry level iMac 21.5 2012, I could get the following config:
CPU: Intel i7 3770k
Mobo: ASRock Extreme 4 z77
Graphics: Nvidia GTX 670 2GB DDR5
RAM: 16GB 1600
Corsair PSU, Coolermaster Cabinet, 1GB HDD etc...
And this is one beast powerhouse. But on further scrutiny of my need and the pro and cons I had finally settled to get the iMac 21.5" 2.9Ghz 650M instead.
There were many reasons why i went for this, some being:
- iMac runs Cooler a lot cooler than the PC. Ambient temp at my city runs about 30-40 C or 86-104 F in summer.
- iMac consumes less electricity. Electric is expensive here. and i normally run my computer 24x7
- iMac Great LED backlit Screen.
- 75% of the Applications I already bought/purchased and use is Mac App.
Obviously, I am going to miss the Musclepower of the PC but with an i5 and 650M the iMac is not a weak Computer either. Its pretty decent and could handle the work i do comfortably.
Thats my Two cents.