FYI: 2x 512Mb Card in SLi = 512Mb Total Memory

[Spunkey]

With all the talk of 512Mb cards around here since yesterday i just thought I'd clear up what seems to be a common misconception.

When you have 2 512Mb cards in SLi configuration they will both store the same* information in memory so although there is a total of 1024Mb being utitlised, only ~512Mb of it is unique data.

This is because having each card storing unique data would cause an extra overhead (card1 having to go through the motherboard to get at info stored in card2's memory) and this would slow down the process beyond any benefit the extra ram would give.

Due to split frame overhead and the texture and render target usage of current games, it's still basically a 512MB framebuffer with two 512MB cards. Lots of data is shared across both boards, even if visible pixel data is different.

This is the reason why the Gigabyte 3D1 with 2x6600GTs on 1 card doesn need double the memory.

* there will be some minor differences i would have thought due to card1 rendering the sky/trees textures and the other card rendering the ground/models, but the vast majority of the data in memory will be the same on both cards

[exAndrzej]

...a total of 1024Mb...

That's all well and good - but will I be able to play Space Invaders without dropping frames ?

That's what I want to know