[jvc26]

To my knowledge bitcoin farmers found the hash rates of the Tesla based ec2 instances far slower than consumer grade high performance graphics cards

[sp332]

I'm not clear on the reason, but desktop GPUs from nvidia and AMD that have similar graphics performance, have very different bitcoin mining performance. The nvidia cards get about half the hash rate of a similar AMD GPU.

[phamilton]

AMD GPUs are better optimized for integer ops, whereas on nVidia integer ops are basically a second class citizen.

Also, AMD tends to be more cores at a lower clock rate than nVidia. For embarrassingly parallel integer operations (like hashing) AMD blows nVidia out of the water.