If you have ATI x1000 series or older, please don't use these drivers. They do not support those cards.
If you have ATI HD 2000 to HD 4000 series:* wget http:// www2.ati .com/drivers/legacy/amd-driver- installer- 12. 6- legacy-x86.x86_64.zip As of Oct 2012, this is the newest driver supporting these cards. For more information, please see [http://support. amd. com/us/kbarticles/Pages/catalyst126legacyproducts. aspx AMD Catalyst™ 12. 6 Legacy Driver]. However, it appears there may be problems running this driver on Quantal due to them not supporting xserver 1.13: [https://bbs.archlinux.org/viewtopic.php?pid=1170787]. Proceed at your own risk.
If you have ATI HD 5000 series or newer:* wget http:// www2.ati. com/ drivers/ beta/ amd- driver- installer- 12-9-beta- x86.x86_64. zip You can also use the newest edition of the ATI drivers that support your card.
Next :* unzip to home directory *sudo sh ./amd-driver-installer- *.run --buildpkg Ubuntu/quantal *sudo dpkg -i fglrx*.deb* sudo aticonfig --initial -f