Why doesnt SLI trick the OS its just one GPU?

[Mario5]

btw I dont know much about SLI and my english is bad, this is just a random thought i had.Why didnt nvidia make a driver wich tricks the os there is just one gpu and therefore all games would utulize both gpus without additional coding. the driver could take the task the game wants it to do and split it over both cards. then combine the finished product and send it to the display.

 

[da na]

because that's not how it works, it has to split the load. How it works is each GPU is assigned a part of the workload/game by the driver that it must render, which wouldn't be able to happen with the OS recognizing only 1 GPU.

[Jurrunio]

SLI is already using multiple GPUs like it's one, what are you on about? You do know the display outputs of cards except the first one (the top one) stop working when using SLI right?

[Levent]

 Both SLI and Xfire work as Primary and Secondary method. Primary card is where frames are sync'd to,  processed data streamed to and where display outputs happen while all that secondary card does is process the frames and can't do anything else. 

[tikker]

Because it doesn't work that way is the boring answer. It's similar to why buying a CPU with more cores and doesn't magically make your game magically use all cores. You have to implement your code in a way that allows the use of more cores, or in this case the use of multiple GPUs.

 

Secondly solving a problem "linearly" with a single GPU/core can be very different from solving that same problem in a parallel fashion with multiple GPUs/cores. You have to distribute tasks, keep track of which tasks are done, make sure they are done in the correct order etc. Something needs to process that logic and who better to implement that than the game developers themselves?

 

Think of this example: you're doing a group project in school. What's the best way to divide the work, finish on time and make sure you're actually doing more work or the same work faster than a single person? I think most of us will be familiar with the fact that 4x the people doesn't always mean 4x the productivity There's not a one size fits all solution for parallel stuff.

[dilpickle]

Same reason why 2 CPU cores can't appear as one.