I have a Radeon X800 GTO (R480) and I had problems with Gnome 3, namely 
it would not run in standard mode,

For that I had to enable modsetting on the kernel.

Device Drivers --->

Graphics support --->

Direct Rendering Manager (XFree86 4.1.0 and higher DRI support) --->

[*] Enable modesetting on radeon by default - NEW DRIVER

Hope this helps,
Clemente

Em 27-11-2012 23:08, Mick escreveu:
> On Tuesday 27 Nov 2012 17:18:43 design [depois das dez] wrote:
>> Fellow Gentooers,
>>
>> although I am very happy running a Gentoo box, sometimes I bump into some
>> difficulties, esp. when updating packages. This time I am having a hard
>> time reconfiguring my video card, which was fine but is not anymore after
>> the last system update I've made. Gnome session goes up as usual but the
>> resolution is not fine and monitor complains about not being in the
>> recommended mode.
>>
>> My video driver is an ATI Radeon 9600 (RV350) and somebody has already
>> updated the section on the Gentoo wiki
>> http://en.gentoo-wiki.com/wiki/Radeon#Kernels_.3E.3D3.0.0  informing that
>> there might be incompatibilities concerning the RV350 firmware. I just
>> don't have enough understanding of the video related parts of the system to
>> tweak and fix this issue. How should I proceed when I have a problem of
>> this sort?
>>
>> How do I know what is the video backend in my system? Is Xorg the only one
>> possible? What can I do to fix this problem?
> The link you provided says that you should disable framebuffer in your kernel
> config.  Have you tried that?
>