I am very close to buying the new 5K Retina iMac but am unsure on what GPU to select? I have heard of many issues and am not too sure on what the situation is? I hope to have this iMac for 5 years plus so would like it to be the best i can afford - therefore i will be getting the i7, 16GB RAM, 512GB SSD configuration. Its just the GPU thats the issue! I am NOT a gamer but i would be using this for video editing (not loads but a reasonable amount. Therefore i would like the best performance for these tasks. I am however concerned about the lagging issues. I am unsure where they pop up? Are they just mission control or are the all over the OS? Also on what specifications, please write what specs you have so that i know what the performance is like with different specs. Also another issue i may have is the noise! I am used to my RMBP being what i call silent 95% of the time (you literally cannot hear a thing!). I also however have a Windows PC that is pretty noisy and that annoys me so how loud is this machine? Also is heat going to be and issue? Thanks in advance! ----------------------- Also be aware that i will be using 2 external 1080P monitors.