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RobMedlock
07-20-05, 02:13 PM
was wondering about something someone will know the answer, if you have 2 cards in sli do they both need a copy of the same information on each card, or do you effectively have the total amount of ram between the cards, so with 2x512 mb cards do you have 1 gb of video memory or 512 as each gpu needs the same info

if so thats silly, what a waste of ram, why dont they just make hyper expensive graphics cards with 2 GPUS?!

Ronin
07-20-05, 02:42 PM
You don't get double the card memory when in SLi. If you have 2 256MB cards, you still have 256MB of VRAM.

They already made dual GPU cards (check Gigabyte and Asus, for example).

NvGod
07-23-05, 12:05 PM
Both cards use its own memory and its not shared. In dual GPU cards each gpu also handles its own memory.

Ronin
07-23-05, 03:44 PM
....

Dude, go Google. You don't have a clue what you're talking about.

jAkUp
07-23-05, 04:54 PM
Yes, even if the card is dual GPU, each GPU still has to access the framebuffer, so you do not have double the ram.

NvGod
07-24-05, 06:50 PM
....

Dude, go Google. You don't have a clue what you're talking about.

I think you didn't undestand what I meant. I'll try to explain my self better next time.

H-street
07-24-05, 07:28 PM
a lot of it depends on the technique..

in AFR both cards render every other frame, so each will need a copy of the textures for the entire scene..

in SFR (or Scissor).. textures are only duplicated where geometries cross the SLI boundary, so in a sense say you get more texture memory in SLI (a lot of it depends on how Nvidia handles it in their drivers)..

trinibwoy
07-24-05, 07:56 PM
a lot of it depends on the technique..

in AFR both cards render every other frame, so each will need a copy of the textures for the entire scene..

in SFR (or Scissor).. textures are only duplicated where geometries cross the SLI boundary, so in a sense say you get more texture memory in SLI (a lot of it depends on how Nvidia handles it in their drivers)..

Actually I thnk in SFR mode the entire scene is sent to the card as well. The driver doesn't know offhand which objects will be rendered by each card (since it doesn't know where they'll end up on screen) and has to submit all information to both cards just as in AFR.

That's why SFR doesn't give any geometry processing boost - both cards end up duplicating the triangle setup stage and translating the entire scene before culling objects outside of their portion of the image.

jAkUp
07-24-05, 07:56 PM
Yes, even in SFR the entire scene is buffered. The game has no way to know where your gonna look.