Welcome, i've just registered to forums because i can't find solution to my problem.
I'm using ubuntu 13.04 with kernel 3.12.4 and my gpu is radeon hd7790 bonaire, to be more specific gigabyte 1GB oc edition. I'm not much acknowledged with open source radeon drivers and... should my gpu use radeon or radeon si driver as open source one? Currently it uses vesa and everything is slow as hell. Animations of window minimizing/maximizing go slow, webbrowsers with enabled hardware acceleration work slow. I expected things to work smooth but it is not. I have 13.04 because on 13.10 i'm getting infinite loop on system boot with ask "what to do? run in safe mode or /other options/?" and when i select safe mode i can't get my desktop to work anyway so i decided to stick with 13.04. Later i might try fglrx but for now i would like to know if there is any option to make open source driver work properly. I've also installed jockey just to see if it can find proprietary drivers for this gpu and it can't detect any which is weird.
Some people say "my hd7770 works fine, your hd7790 should too" which is not true because there is huge difference between hd7770 and 7790, these are two totally different gpus.
Concluding: How to force proper open source driver to work with my gpu?
And as always in first post from non-native english speaker: sorry for my english which might be not so well