I hope I'm not off topic here, but this seemed like a good place to ask something like this.
I've been hearing about SLI and Crossfire for a long time and how support for it is lacking.
I never could understand why were the developers ones that needed to support it.
GPUs are immensely parallel things. They have thousands of cores that run same code at the same time (generally speaking). The game will run with same code on a GPU with 100 cores and with 1000 cores, it will just scale itself differently.
I want to know what stopped the GPU companies from dealing with this within the drivers.
Why not have the driver detect two physical GPUs and present them to the system as a one logical GPU? It would then make sure that the workload is evenly distributed, while using the SLI bridge to synchronise and exchange the data across the GPUs as needed.
If this was really that great as it looks to be, I'm sure they'd be doing it that way, but they aren't. My question is, why not, where does this idea fall apart?
Only reason I can think of is that the GPUs can't handle both the communication with the CPU and with each other fast enough to make the whole thing feasible, and in order to do so, architectural changes would be need which would not yield any improvements in single GPU systems, but only multi GPU system, which would be far, far rarer.