I had a computer that had no graphis memory and had very slow renderings. So I installed a gtx 550ti from egva using the n vedia chip but m rendering time is the same. Do I need to setup up something in PS5 to use the memory or is it automatic? The video card has 2 gig of onboard memory.
If it is a supported video card, it should be automatic.
If you're referring to "high quality" or "draft quality" 3D rendering in Photoshop CS5 then your graphics card will have no bearing on the render time - that rendering is done by the CPU and with regular system memory. The graphics card certainly should improve "interactive" 3D rendering and some other features of Photoshop, though.