I'm benchmarking some software and am looking for cards that are better at parallel multiplication vs parallel addition.
Is there any prior work that may have this information?
What GPU features should I look for?
That depends on your application, obviously. If you intend to run Matlab or Python on a single machine, and you're looking into which graphics card to buy, multiplication vs addition should not matter much.
I that situation I would recommend an Nvidia card which features CUDA. For CUDA, there are lot of libraries available which make it easy to adapt existing code to run on the GPU. Of course you can add more GPUs for more performance using SLI whatever your Card requires.
Mathworks has a nice overview that will help you getting started. For Python there is PyCUDA, but i have only very limited experience with that. For Java and C++ there are options as well, bu I've never used those.
The downside of all this is that your code will be less portable as you will need to use gpuArrays (in Matlab), so if someone without a CUDA-Configuration attempts to run the code, it will fail. I have yet to find an elegant way around this (!= my boss sitting at my desk...)