Miners use AMD cards because they have better integer performance, unless I'm mistaken.

It depends on what you are mining, and your cost modeling. For instance, NVIDIA cards have better memory bandwidth and both dagger-hashimoto and equihash are memory hard algorithms, and NVIDIA cards have better expected resale value (though this will vary based on your expected sales channel.)

AMD is generally more popular among hobbyist miners, I think, because early on they had a performance advantage in Ethereum and hobbyists tend to follow each other like a herd because they have limited time to do experimentation and exploration (and this is not a criticism of them, they have day jobs and it takes a lot of effort to even get miners going, let alone optimize them across multiple parameters.)

I thought they use AMD cards because they consume less power

Those two statements are basically equivalent when it comes to mining. cost/hash/second is the metric you optimize for. AMD cards can do the integer operations required with less power (and faster!)

NVidia actually consumes less power in most games.

But AMD cards use less power with integer performance.

This is the reason, Nvidia is good for floating point. Which is why people use them for deep learning.

The main reason is library support. Still no widely supported (or ported) equivalent to Cuda/CuDNN for AMD.

Power does not matter that much if you spend $3 of it to earn $100 every month. It mostly depends on payback time.

nVidia is close to the only useful thing for deep learning. Which is also kinda a big thing.

Mining with GPUs hasn't been profitable since around 2014. GPUs have largely been replaced by ASICs (although certain coins are still mineable with GPUs, like Ethereum[1], as discussed in the article). Bitmain[2] is (AFAIK) the manufacturer of ASICs for mining.

[1]: https://motherboard.vice.com/en_us/article/59zdjq/an-idiots-...

[2]: https://www.bitmain.com/

Mining for Ethereum is entirely GPU based. Mining for Bitcoin/Litecoin is entirely ASIC based now.

If mining is profitable at all, why wouldn't a manufacturer of ASICs or GPUs run its own mining operation?

For the same reason why shovel manufacturers don't dig their own gold. Why take the risk of uncertainty that comes with the whole mining operation?

Pain in the ass to run. Competition will torch your facility if you don't spend enough money and effort on security. You're going to need your own power plant, etc.

If you are the manufacturer, why not let the customer take the risk? You are planning and spending years ahead, why gamble more than you need on cryptocurrency price?

i wouldn't be surprised if they do.