[–] TryingToVoat ago
I'll explain this by explaining why we have AMD. See a company typically doesn't want to put all their eggs in one basket, especially if it's in another company. So when Intel was trying to pitch their 8080 chip to IBM, IBM wanted to make sure if Intel died another company could make it, so AMD made the cheaper version and was given the stuff. Same thing with board manufacturers happened. Instead of being the only one who could make an nVidia card, several people can.
[–] mavric 0 points 1 point 1 point (+1|-0) ago
It's the same reason that the same companies design motherboards for the Intel/AMD chipsets. nVidia/AMD provides the GPUs and gives the board manufacturers strict guidelines as to how the boards will be configured initially before the board manufacturers apply custom modifications like their own BIOS, cooling systems, etc. This gives the GPU manufacturers an advantage. Firstly, the companies they license their GPUs out to have a massive market share across the globe. This would be much harder to do if the production and distribution was handled by just one company. This is also beneficial to the board manufacturers, as it keeps them in business and creates jobs etc. It also eliminates nVidia/AMD having to do all of the warranty repairs. All in all it's a very mutual relationship that nets major profits on both ends.
[–] binky ago (edited ago)
A video card has some pre-made parts and some that are made by the manufacturer. A GPU, for example, is premade. When it's sold the company that made it also provides a set of instructions for how it can be used. The power it needs, the way it has to be connected to the board, how much memory it can use and how the memory must be addressed are all part of the GPU. Some video card companies buy certain parts, like memory. Some video card companies have those parts made to their own specifications. Some make their own. But all the memory that connects to a GPU has to be addressable, or it has to connect to a custom chip that makes it addressable.
Different companies sell very similar cards because they're using the same pre-made parts, which have specific requirements that are best met by other pre-made parts. Other companies choose to make their own, or buy different components, which can be tied together in different ways.
Certain GPU's are able to support certain outputs. It's possible to add support (by adding a GPU or a chipset) but expensive and usually un-necessary. So that GPU will almost always be paired with that set of outputs.
As mavric pointed out licensing is also a big part of it. Sometimes a chip comes with a requirement that it be used in a certain way.