590 GTX or SLI second card memory usage

[remanz]

as title states, how do I know the game is using my 2nd card's memory ? or how do i configure it so that it will take advantage second card's memory.

It seems a bit odd that both card's memory usage indicator are always the same (linked together). I am refering to 4 box SWTOR. if first card is used for 1310 MB. 2nd card's usage is also 1310MB. Does that mean total 2620MB memory used ???

I used the isboxer+innerspace setup to create 2 game profiles. 1 profile used monitor 1. 2nd used for monitor 2. But how do I make sure GPUA is for first monitor and GPUB is for 2nd monitor ?


I recall MiRai's multiboxing science mentioned he was able to utilize 2nd GPU's VRAM.

[remanz]

ok. since no one answered, I will explain after my own investigation.

SLI 1.5GB x2 != 3GB

The limitation of SLI is that each GPU can only work with its own VRAM. So Card A cannot work with card B 's memory. and When both cards are working, pixels are duplicated in both cards memory for each GPU.

So I will never get 3GB worth of pixels in my GTX 590. It is a 1.5GB card, not 3GB. True SLI works the same. if you do sli 570 x2, you still only have 1.25 GB VRAM.

[MiRai]

Sorry, I remember seeing this thread and wanted to come back to it but forgot.

You're correct, when cards are SLI'd their onboard memory is not added together and it is shared (duplicated) between them.
The GTX 590 has always been marketed with 3GB of memory but it's really 1.5GB + 1.5GB which actually can't be added
together.

I don't know if you can utilize the second GPU at all if you disable SLI on the card itself. Maybe the 2nd GPU is connected to
the second DVI port (I have no idea). If it is then you can create game profiles within InnerSpace's configuration to take
advantage of different monitors in which you plug into different GPUs. If you are able to use the GPUs separately they're
each an underclocked GTX 580 when not SLI'd.

Dual GPU cards are a headache and they're never recommended to use with multiboxing.