VRAM sli/xfire vs dual GPU cards.

[Unclescar]

It's a semi-commonly known fact that having two 3gb cards, like a 780 in SLI, does not actually result in 6gb of useable vram, and having two 2gb cards doesn't mean you have 4gb of vram.

Then you see dual GPU cards such as the 295x2 (two R9 290x 4gb) listed as an 8gb card, and the titanZ (two Titan Black 6gb) at 12Ggb.

However, are these not just SLI and Xfire setups on the same PCB?

I'm just mildly curious since so many misconceptions seem to be thrown out as fact. How does it actually work?

[helping]

They are, and they work exactly like standard crossfire/SLI

 

Just the way they choose to market it. It technically is 8 and 12 GB respectively, so they're not really doing anything wrong.

 

You pay for 12GB of VRAM, you get 12GB of VRAM, so the costs and product reflect 12GB of VRAM. How they're used is a different issue entirely, nonetheless the labeling is correct. 

[Enderman]

Yes it is exactly crossfire/sli. The vram listings are total ram, so for each GPU it is 50% of 8 or 12 or whatever it says.