- Nvidia GTX 650 (2012)
- On-board AMD (Stone Age)
- AMD R7 260x (2013)
In general a fancy, powerful card offers no advantage for an audio system. In the future it may be possible to use the processing power of the GPU for DSP, but at the moment that's not been implemented.
It's possible to take some of the graphics load off the CPU by using the 3D processing power to accelerate 2D. I can hear when this is happening because the graphics card fan speeds up. This only uses a fraction of what the card is capable of, so a more powerful card wouldn't improve performance.
The criteria that have been relevant to audio performance are :
- Can I use a realtime kernel?
- What is the kernel scheduling latency?
- Do Xruns happen when clicking, using alt-tab or switching workspaces?
- What is the Xorg CPU usage?
- Is there screen tearing?
- Does Kdenlive (a video editor) play back smoothly?
- Nvidia GTX 650
Apparently the situation has improved recently. It's now possible to use proprietary drivers with a realtime kernel. This probably happened on the day I bought the AMD R7. At that time an RT kernel only worked with nouveau drivers, which weren't always reliable. So I went to
- On-board AMD
Fine for audio, not good for video.
- AMD R7 260x
I started with the AMDGPU drivers which take some configuration to get working with this card. AMDGPU support for this particular card is considered 'experimental'. They worked, but I noticed Xorg was using a lot of CPU. Without anything demanding loaded Xorg CPU was normal at 1 - 2%, but when I loaded Ardour it went up to around 60%. That didn't seem right.
This was resolved by using the radeon drivers. Now Xorg starts at below 1% and goes up to around 20% with Ardour loaded.
On my system I can say that an AMD R7 + radeon drivers is the best of the options available. Newer AMD cards should work well with AMDGPU.