In the Save Image dialog there is a Banded Rendering option. That can be used to split the render job up into bands (all on your machine), each band then has a reduced memory requirement. This may help with large images from complex models.
Depending on what you are aiming for visually you may find that using the Render tools give you more options.
Depending on what you are aiming for visually you may find that using the Render tools give you more options.