If you have a certain kind of Geforce 9600 like this one, all you have to do is flash the BIOS and it will unlock the unused shader units and the 2 memory units that Nvidia has deactivated. To simplify this you are adding 128MB of RAM and some extra hardware pipelines only by modifying some software.
Unfortunately the graphics card that this hack works on isn’t very common but if you can manage to get a hold of one you can save a lot of money and get a huge performance increase over the 9600.