Unfortunately you cannot update your drivers from AMD. AMD only offers 'generic' drivers which will not work correctly with the Sony custom drivers, read here ..so if Sony supports Windows 8 for your version laptop, then they will have drivers for it. Not all laptops are Win8 supported and should use the OS it was designed for. There is a Sony Viao laptop forum where you may get some ideas/help.
Intel I7 960 @ 3.87ghz *Intel DX58SO *AMD R9 290 4gb *Corsair TX650M *2x4gb Corsair XMS3 *WD Black 1TB *Windows 7 Home Premium 64bit ***Asus N71Jq laptop *Intel I7 720QM Processor *Mobility Radeon HD5730 1gb *8gb Ram *Windows 7 64bit ** Toshiba P75-A7200 * Intel I7-4700MQ * Windows 8.1 64bit
***** cetera fallunt, ludere mortuus ******