Tried an older driver from the AMD website (version 12.4 ). It also didn't work.... The installation log :

root@lap1:/home/pubudu/ati# sh ./amd-driver-installer-12-4-x86.x86_64.run --buildpkg Ubuntu/quantal
Created directory fglrx-install.URF3MZ
Verifying archive integrity... All good.
Uncompressing AMD Catalyst(TM) Proprietary Driver-8.961.....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
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 AMD Catalyst(TM) Proprietary Driver Installer/Packager 
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Generating package: Ubuntu/quantal
Package /home/pubudu/ati/fglrx_8.961-0ubuntu1_amd64.deb has been successfully generated
Package /home/pubudu/ati/fglrx-dev_8.961-0ubuntu1_amd64.deb has been successfully generated
Package /home/pubudu/ati/fglrx-amdcccle_8.961-0ubuntu1_amd64.deb has been successfully generated
Removing temporary directory: fglrx-install.URF3MZ
root@lap1:/home/pubudu/ati# sudo dpkg -i fglrx*.deb
Selecting previously unselected package fglrx.
(Reading database ... 157665 files and directories currently installed.)
Unpacking fglrx (from fglrx_8.961-0ubuntu1_amd64.deb) ...
Selecting previously unselected package fglrx-amdcccle.
Unpacking fglrx-amdcccle (from fglrx-amdcccle_8.961-0ubuntu1_amd64.deb) ...
Selecting previously unselected package fglrx-dev.
Unpacking fglrx-dev (from fglrx-dev_8.961-0ubuntu1_amd64.deb) ...
Setting up fglrx (2:8.961-0ubuntu1) ...
update-alternatives: using /usr/lib/fglrx/ld.so.conf to provide /etc/ld.so.conf.d/x86_64-linux-gnu_GL.conf (x86_64-linux-gnu_gl_conf) in auto mode
update-alternatives: warning: skip creation of /etc/OpenCL/vendors/amdocl32.icd because associated file /usr/lib/fglrx/etc/OpenCL/vendors/amdocl32.icd (of link group x86_64-linux-gnu_gl_conf) doesn't exist
update-alternatives: warning: forcing reinstallation of alternative /usr/lib/fglrx/ld.so.conf because link group x86_64-linux-gnu_gl_conf is broken
update-alternatives: warning: skip creation of /etc/OpenCL/vendors/amdocl32.icd because associated file /usr/lib/fglrx/etc/OpenCL/vendors/amdocl32.icd (of link group x86_64-linux-gnu_gl_conf) doesn't exist
update-alternatives: using /usr/lib/fglrx/alt_ld.so.conf to provide /etc/ld.so.conf.d/i386-linux-gnu_GL.conf (i386-linux-gnu_gl_conf) in auto mode
update-initramfs: deferring update (trigger activated)
Loading new fglrx-8.961 DKMS files...
First Installation: checking all kernels...
Building only for 3.5.0-17-generic
Building for architecture x86_64
Building initial module for 3.5.0-17-generic
Error! Bad return status for module build on kernel: 3.5.0-17-generic (x86_64)
Consult /var/lib/dkms/fglrx/8.961/build/make.log for more information.
update-initramfs: deferring update (trigger activated)
Processing triggers for ureadahead ...
ureadahead will be reprofiled on next reboot
Processing triggers for bamfdaemon ...
Rebuilding /usr/share/applications/bamf.index...
Setting up fglrx-amdcccle (2:8.961-0ubuntu1) ...
Setting up fglrx-dev (2:8.961-0ubuntu1) ...
Processing triggers for initramfs-tools ...
update-initramfs: Generating /boot/initrd.img-3.5.0-17-generic
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place