do two 256 mb cards in SLI work as one 512 mb card?

[slugg]

As the title asks, if I run two 256 mb cards, is this the same as running one 512 mb card? Speed differences aside, how is the memory handled?

 

[Dainas]

technically no, but when I upgraded from a single 7800GTX to SLI i noticed the hiccups I once in awhile encountered(that have been attributed to memory swapping) in UQ quake 4 stopped... Officialy I say no but ??? not compleatly sure what goes on in SLI.

 

[MDE]

No, it'll be faster although the cards will still only have 256MB RAM each as you don't combine the cards' RAM in SLI.

 

[nitromullet]

Originally posted by: Dainas
technically no, but when I upgraded from a single 7800GTX to SLI i noticed the hiccups I once in awhile encountered(that have been attributed to memory swapping) in UQ quake 4 stopped... Officialy I say no but ??? not compleatly sure what goes on in SLI.

You know that 3dfx invented the original SLI, and they also had a series of cards called "Voodoo"... Coincidence? I think not.

Serioulsy though, both cards in SLI must hold all of the textures they each need in memory, so chances are that they are holding duplicate data in their memory is high. However, depending on the SLI mode, say SFR (where they split the screen horizontally), if the top and bottom half of the screen are extemely different in terms of textures, they may not both have the same textures in memory. This, theoretically, would make it appear as if their was more then 256MB total RAM. This is a very basic explanation of this, and is also about the extent of my knowledge.

 

[slugg]

hmm ok well how long do you think 256 meg cards will last? should I bite the bullet for a 512?

 

[MDE]

If anything I'd wait for R580 or G71.

 

[nitromullet]

Originally posted by: slugg
hmm ok well how long do you think 256 meg cards will last? should I bite the bullet for a 512?

If you're talking about the 512MB GTX, you probably won't get hold of one for anyhting resembling a reasonable price. On the otherhand, if you're talking about the X1800XT, I'm pretty happy with mine. Then you could also wait until the new cards come out, but I predict that will be closer to a 3 month wait as opposed to availability in Jan 2006.

 

[slugg]

i'll probably wait it out then, hehe

but definitely go 512 mb? or dual 256?

 

[otispunkmeyer]

two gtx's in sli will be faster than one gtx 512, and no running 2 256mb card doesnt equal one 512 card in SLI

 

[aatf510]

Originally posted by: slugg
i'll probably wait it out then, hehe

but definitely go 512 mb? or dual 256?

If you read Anandtech's review, CURRENTLY - the extra 256MB memory makes zero differences.