Hello
I bought my new iMac 27'' 3.2Ghz 8 gb RAM with GT 755m.
I am not a big gamer but I do 3d graphics. In short , no graphic card out there stands a chance however powerful in my hands. I am using the open source 3d app Blender. Blender has a real time render engine that maxes my GPU in a few seconds.
One thing to note here, is that m , that indicated that the version of the GPU is the mobile version, meaning less power consumed (around 50%) but also less performance to the equivalent desktop model (around 2 times).
So if you want to get a computer that will have a very powerful GPU iMacs are definitely not it! A pc will serve you much better. To give you a precise picture , my GPU on this iMAC performs around the same with my pc's at work GTX 650 and that pc is 1 year old.
iMac GPUs are just powerful enough. Another thing to note here is that GPUs has a life of 1 year. 2 -3 years I hear here is very much optimistic even for the most powerful GPUs. But it all depends on the game.
Personally I dont care so much because I know there are people that still play games on Amigas, are those not gamers ? So the whole "Macs are not for games" leaves me rolling my eyes
😀 Sure if we exclude macpro every other mac out there comes with gpus too weak to keep you on the cutting edge of games for more than 1 year. But then there like tons of games out there that are way more forgiving.
I chose iMac because my previous computer was also an iMac and I was very happy with it. The way I see it my new iMac is 8 to 16 times faster than my 7 year old iMac and thats enough for me. I know that if I wanted the best performance at 2000 euros I would have bought a PC. But I love the 27'' screen and I can live with less performance.
An example of comparing the desktop version with the mobile version of 780 can be found here
http://gpuboss.com/gpus/GeForce-GTX-780M-Mac-vs-GeForce-GTX-780