Can't access gpu rendering

I am new to blender but looking to speed up my render times. The GPU option in cycles seems to be evading me no matter what I do. I have a Power Mac (2012) with two graphics cards Radeon HD 5770. Updated CUDA drivers. No option in system preferences except CPU. Please help.

CUDA is NVidia only so your Radeon is not supported.

Thanks, does that mean that i have to get a NVdia card in order to access GPU rendering? because it would seem that only the older models of my computer are compatible NVdia. Is there any way around this? I can’t get a new computer!

Hi, there is a thread about GPU rendering on AMD card, but it doesn’t seem to be really faster than CPU.
What is your computer model ? laptop or desktop ? all in one or not ?

thanks CrusT, i have two macs one is an Imac (intel iris pro), the other is a Power Mac with two Radeon Graphics cards. Just so i get it straight, are you saying that unless i have Nvidia card the gpu option won’t have any benefits?