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Is Single GTX 580 3Gb better than SLI GTX 580 3Gb with GTX 580 1.5Gb?

Last response: in Graphics & Displays
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September 28, 2011 1:35:36 AM

Hi

I'm currently building a gaming desktop and I was looking to SLI my EVGA GTX 580 3GB with the ASUS GTX 580 1.5 GB.

I understand the consequence of doing this involves essentially losing 1.5GB from the 3GB card.

My question is though: Is it worth it? What I mean is: Will a single 3GB 580 card run more efficiently and provide better performance than running an SLI setup with the 3GB 580 and the 1.5GB 580 where 1.5 GB of VRAM are lost?
a b U Graphics card
September 28, 2011 2:09:55 AM

the SLI 580 (3gb combined) will be a faster setup.

however if u got another 580 /w 3gb on it, that setup would be faster again (6gb total)

a b U Graphics card
September 28, 2011 2:13:20 AM

.....whoa.....thats not how it works


if you add a 1.5 gig card BOTH cards will only utilize 1.5 gigs.....

and in that situation you will only be hampered by a super resolution like 5700x1200

if you do not plan on using vision surround i see no problem with going for the asus caard
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a c 538 U Graphics card
September 28, 2011 2:21:07 AM

SLI is faster, IF you have the CPU to handle it without bottlenecking. The extra memory will only matter at ultra high multiple monitor resolutions.

If I were you, my vote would be for the single 3GB card to save money and electricity, and still kill any living game you throw at it. The GTX 580 is the ultimate video card for this generation. The SLI will be faster, but the single card is still more than enough. All the same, you will still have the option to upgrade to a second 3GB card in the future as well.
a c 214 U Graphics card
September 28, 2011 2:41:56 AM

A GTX580 SLI is always going to be more powerful than a single GTX580 with x amount of VRAM.You only have so much power a single GTX580 can deliver.You will see a lot more performance with SLI than a single.And unless your using 3D surround or Eyefinity than the extra RAM that you loose won't matter much at all.
a c 169 U Graphics card
September 28, 2011 2:52:50 AM

if you add a 3gb card and a 1.5 gb card the amount of useable ram will be the lowest cards 1.5gb, you will be wasting 1.5gb of ram from your 3gb card.
a b U Graphics card
September 28, 2011 3:21:19 AM

yes that is correct. combining a 3gb card with a 1.5gb card will result in 3gb total avaliable RAM (loosing 1.5 from ur 3gb card)

2x 1.5 gb cards = 3gb usable RAM
3gb Card + 1.5 gb Card = 3gb usable ram
2x 3gb Cards = 6gb usable ram

Ranked in order of performance lowest to highest

Single 580 1.5gb
Single 580 3gb

<insert big performance gap here>

Twin 580 3gb combined (either 2x 1.5 or 1.5gb + 3gb)
twin 580 6gb combined (2x 3gb cards)


the video ram makes a bigger and bigger difference the larger the resolution you game in. (Eyefinity and Surround will benifit the most from more video ram)
a b U Graphics card
September 28, 2011 4:24:49 AM

^Thats still not how it works, the cards run in parallel, both sets of ram store identical sets of data, so you are limited by the card with less vram.
a c 169 U Graphics card
September 28, 2011 7:31:30 AM

HugoStiglitz said:
yes that is correct. combining a 3gb card with a 1.5gb card will result in 3gb total avaliable RAM (loosing 1.5 from ur 3gb card)

2x 1.5 gb cards = 3gb usable RAM
3gb Card + 1.5 gb Card = 3gb usable ram
2x 3gb Cards = 6gb usable ram


Wrong, wrong, wrong. 2 x 1.5gb cards still = 1.5gb useable, everything in the ram of both cards is mirrored, they both contain the same information, 2 cards doesn't increase the amount of useable memory. a 3gb + 1.5gb card still has 1.5gb useable memory as the data in both has to be mirrored and since the 1.5gb card cant mirror 3gb, the total vram available is of the lowest memory card.
a c 214 U Graphics card
September 28, 2011 10:25:14 AM

^+1
a b U Graphics card
September 28, 2011 11:34:43 AM

Add to that the fact that while SLI/Crossfire has a better average performance than single cards, they do feel a lot worse than a single card setup when the frame rates are low. Sometime Vsync will also hamper multi-card setups. From personal experience, if you have the money for a single powerful card, buy that.
a c 214 U Graphics card
September 28, 2011 11:44:22 AM

The OP already has the most powerful single GPU you can buy.
January 31, 2012 7:38:32 AM

I just stumbled upon this thread and I'm building a PC for a friend and we have been considering getting 2 GTX580s 3GB from EVGA. He has the money for 1 or 2. My question is, should we just get 2 cards? One comment here said vsync will hamper multi-card setups. Is that true? My friends uses vsync in all his games. Anyways 2 cards or 1? Going for the best performance. Price isn't a factor.
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