So I have a iMac mid 2011, with windows 7 64 bit installed. I wanted to know if I can upgrade my GPU from the default 512mb card to a 1gb card or higher, and if so which cards do you recommend. Thank you in advance.
You can't upgrade the card after buying the computer, you have to customize it before buying it. The GPU is soldered to the mother board, so you can't just do it yourself, Apple has to do it themselves.
You can upgrade your GPU. iMac '11 is the last iMac with upgradeable GPU, could only use another iMac '11's GPU though maximum is HD 6970m, which still is not fast by today's standards. Would be better to get a new iMac if you really NEED speedy GPUs. Too much trouble to open up your old iMac.