I am working on an OpenGL application on my laptop. My app shows lots of black and white unrecognizable patterns when I try to display a monochrome image (quite large). I have a hunch that it could be that my old Geforce Go 7950 GTX (512 MB) is too old for my app, and thinking the problem was due to framebuffer object size limit - is there a way to find out what the largest FBO can be?
There is no maximum limit to framebuffer size in OpenGL. The limit is the largest texture or renderbuffer that you can attach to it.
There is however a maximum viewport size, get it using GL_MAX_VIEWPORT_DIMS, however according to the OpenGL specs, the viewport is silently clamped the max size anyway and shouldn't cause glitches. https://www.opengl.org/sdk/docs/man/html/glViewport.xhtml