Because they sell "professional" Quadro/Tesla cards with this feature enabled at enormous prices.

Aaaah... so this probably is not about Linux vs. Windows, but rather actually about 'GeForce GTX 560 Ti' vs. Quadro. They aren't worried about driving people away from Windows, they are worried about cannibalizing Quadro sales.

There is probably a lot of use cases for many monitors that don't really require Windows (perhaps pro power-users, like traders, who need lots of browser windows open at once), so they need to ensure that their premium cards retain their edge even on Linux.

That makes much more sense.

But how many of those users would need to use NVIDIA's drivers? As I understand it, the benefit of NVIDIA's drivers over Noueveau is performance, not basic hardware support. If all you need is many monitors for web browsers, then you should not have a problem using Noueveau.

> But how many of those users would need to use NVIDIA's drivers?

That's a good point; I cannot say. Perhaps they think they are dealing with people who think 3D performance is necessary, or dealing with people (IT organizations?) that prefer 1st party drivers to hardware savings.

I don't think Microsoft is really involved in this though.

This sort of logic completely baffles me.

People buy hardware to use their advertised features. If you are the type of person that only needs 2D rendering and video then you should use an Intel GPU. I would assume people who buy a state-of-the-art dedicated GPU want to use them for actual 3D acceleration.

Or possibly the advertised feature they're interested in is 'ridiculous number of attached monitors'. Intel GPUs generally only have a couple of display connectors; if you want a card with a lot of physical ports you'll want to buy a discrete GPU whether or not it support 3D acceleration.

I have some experience here. With Nouveau, XRandr works out of the box -- great if you have one card. With the proprietary driver, no such luck (last I checked). On the other hand, my workstation has two cards, and XRandr is not up to the task; it was back to Xinerama and playing with xorg.conf.

I'm using the proprietary driver, it has had XRandr support for a while now.

Ah, my information is a bit out of date (at least a year, maybe more?). Thanks.

Even some of the Quadro cards (Q2000m in my personal experience) won't do more than 3 displays, and to do that requires changing bios settings which make games unplayable for the most part.

Yeah even Windows98 could run 9 displays. From the sound of it though, it looked like it was about presenting a single display to the OS across multiple GPUs. That's significantly different than Windows' built-in multi-display support.

Think full-screen apps that call APIs that aren't going to work across screen boundaries.