I have a desktop ACER, with an Ati Radeon HD 3650 (RV635). I always have to boot with "nomodeset" checked. It happens to me with ubuntu 12.04 and it's happening now, with ubuntu 14.04. I have installed the free drivers, but when I boot, ubuntu always use Gallium 0.4 on llvmpipe (LLVM 3.5, 128 bits). The browser doesn't work well and the videos run very choppy.
How could I make to work the proper driver for my graphic card? Anybody can help me?
(Edited) On what I'm reading I finded that perhaps I have an hybrid graphics. I'm not sure. How can I know?
(Edited 6-12) I continue making research. As the_Seppi said, my graphic card isn't supported yet by the propietary drivers, as can be seen in this site http://wiki.cchtml.com/index.php/Hardware. Ok, it's another detail. I will continue researching
(I apologise for my bad english)
At last my problem was solved in an indirect way. I was worried because the performance of all the computer was very poor. I had an old graphic card, as you see, with no propietary drivers working to get acceleration. I have installed the free drivers (gallium something on llvmpipe). The solution to get a better performance have been to install gnome over ubuntu 14.04 and forgot unity. Now everything seem to work perfectly. I don't woory about the 3D effects. Now everything is fine for me.