Crossfire vs. SLI

X

xCWolf

[H]ard|Gawd
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So what increases performance more?

Crossfire, or SLI? like lets say we have two equivalent cards what is going to perform better with 2+ of them?
 
about the same.

overall, i would say sli because of amd's latest f up's in deus ex
 
In this generation of cards Crossfire Scales better but that doesn't always equals better performance. Overall the higher the resolution the better amd does compared to nvidia, especially when you consider the price difference. Either way both are great. What I would try to find out if I were you is which would perform better for what you do or plan to do.

What resolution will you be running?

What games will you be playing?

How much is your budget?

What are the specs of your rig?
 
resolution will be 16:9 unless I can find a great deal on a 3 monitor setup, games will be BF3 COD and Skyrim. budget is just under 350 and the rig has i7 920, 6gb ddr3, 3way sli + physics evga classified board and currently a radeon 5770 ( which needs an upgrade)
 
Both have advantages and disadvantages. Im pretty sure the two graphics cards have to be the same for SLI and with Crossfire they dont have to be exactly the same. They have to be in the same GPU family. Someone correct me if I'm wrong. I've never played with AMD's cards.
 
xCWolf said:
resolution will be 16:9 unless I can find a great deal on a 3 monitor setup, games will be BF3 COD and Skyrim. budget is just under 350 and the rig has i7 920, 6gb ddr3, 3way sli + physics evga classified board and currently a radeon 5770 ( which needs an upgrade)
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with a $350 budget I think you may be better off going with a single high end card. Just my .02

$350 will get you a pair of 6870's, which don't beat a single 6970 which you can get for slightly less. If you can get higher performance without SLI/Xfire, you are ALWAYS better off. This also leaves you for a much higher end upgrade possibility. If you end up going with 2 lower end cards, your only real option is going to be to upgrade both. If you go with 1 6970 for example, you have the option of adding a 2nd later.

Performance for your money, http://www.newegg.com/Product/Product.aspx?Item=N82E16814161356 is about the best bet for your $350. (other than finding one cheaper somewhere else or used, or if you are REALLY lucky, a used reference 6950 to unlock.)
 
Two HD6870s are typically about 50-60% faster than one HD6970 - they're way ahead.
Crossfire scaling is normally taken at 95% (except in games where it's broken) and SLI normally at 85% (except in games where it's broken).
 
I would without checking references say that if you game at 1080p or below than Xfire would be a good solution but anything higher, I would go with a 69xx based solution with more memory.
 
I think the 580s generally have a bit more horsepower, although some games don't use it and the 6970 can actually edge ahead or be dead-even. So two of those will give you a bit better performance, but overall I think the actual performance of SLI/Xfire, as a technology, is very similar at this point. It really can change from driver release to driver release.
 
One thing to also consider is Crossfire is fullscreen only, SLi can work in fullscreen and windowed.

But right now Crossfire scales slightly better then SLI, but doesn't mean SLI isn't scaling well.

I have 5870 CF and I enjoy it. My only complaint is that it only works in Fullscreen. I play MMOs in windowed so its annoying not being able to use both GPUs. But this may not affect you.
 
I'd say the reverse, the HD6970s have a lot of "horsepower" but aren't able to use it at lower resolutions. At higher resolutions, putting it to effect enables the HD6970 to run alongside the 580.
 
qbanb8582 said:
One thing to also consider is Crossfire is fullscreen only, SLi can work in fullscreen and windowed.
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Crossfire does not work in windowed mode? Seriously? Huh... I had no clue and that really sucks. I play WoW in windowed mode so I can use my second monitor for internet, videos, etc. Interesting...
 
Oh well. The games where my FPS really matters (FPS) all get played in Fullscreen so no biggie. :)
 
AMD has had quite a bit of driver issues with CF lately, and while scaling in some games can be great, there's also lots of stutter and bad scaling so in some games CF is mostly useless. Can't say much about SLI since I haven't tried it, but I doubt it's a picknick out there either. Personally after trying 6950 CF I really wouldn't go any lower due to stutter issues. 6950CF is a bargain when it does get the job done, but that's like only half the time. GTX 580 SLI on the other is for those that don't care about the budget, and if SLI don't work, you still got the fastest single card available.

On the other hand I would only recommend SLI/CF for 30" or multimonitor gaming, and then you should buy cards with 2GB or more memory, so either 69xx or GTX 570/580 with double VRAM.
 
Half the time is an exaggeration, i'd say 85%+ of the time crossfire works well in modern games, there are only a few recent examples of it not functioning properly.
 
The problem is that it's usually the new games you want to make use of CF, and they're the ones not working properly. AMD is just taking too long to get their drivers working. It just feels like I should wait several months after release to expect a somewhat polished experience.
 
I can only think of one recent title (DEHR) that doesn't work properly in crossfire. Two if you count BF3 but with the latest updates that too seems to work OK.
 
DualOwn said:
about the same.

overall, i would say sli because of amd's latest f up's in deus ex
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BS, Crossfire is far better this round. Minimum framerates seemed to scale much better than sli for me in a wide variety of games. AMD also seems to get hotfixes and application profiles up faster. I wasn't at all impressed with sli.

I love my GTX570 but the jump to two was disappointing. I can't say that about 6950.
 
Remember who you're talking to. DualOwn is not likely to write anything factual about AMD hardware.
 
General Lee said:
The problem is that it's usually the new games you want to make use of CF, and they're the ones not working properly. AMD is just taking too long to get their drivers working. It just feels like I should wait several months after release to expect a somewhat polished experience.
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Nvidia releases one WHQL every three months for the most part. I think that the only option for GTX460 for almost three months after its release was a shoddy beta. Thats just not cool if you ask me.

Nvidia's beta drivers aren't exactly the most stable thing in the world. I gave up on trying those a long time ago.

Pushing out quick updates isn't Nvidia's strong suit.
 
I've read that article. What's your point? It's well proven that the HD6900 scales positively with resolution, whereas Fermis tend to scale less so (and negatively for the 560Ti)
 
I've been in both camps, currently running with AMD as you can see.

My son's computer is 580 GTX in SLi and my backup is 280 GTX in SLi.

I have to say, when AMD wants to, they will correct things and churn out proper drivers and Crossfire profiles to meet the demands.
I am very impressed with the scaling in CFX with my current setup.
That said, AMD has been teh suck in Dead Island, Rage, and BF3......Dead Island just got a CFX profile, Rage has been FUBAR'd since the jump, and the first CFX for BF3 was a bust.

Things got fixed in BF3 in a hurry.

You can say what you want about nvidia, but I still think their driver team is better.....SLi just always seems to work, less hassle.........my 2 cents only.

Surround is a bit easier to set up at the jump, but once you've mastered EyeFinity it works just fine too......both triple screen solutions work very, very well.:D
 
samuelmorris said:
I've read that article. What's your point? It's well proven that the HD6900 scales positively with resolution, whereas Fermis tend to scale less so (and negatively for the 560Ti)
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Therefore, the HD6990 loses at high resolutions against the GTX590?
Theory and Practice. I understand what you mean, theoretically, the AMD 69xx Single-GPU are faster the higher the Resolution, which only uses this in practice? SLI supports more games, do you understand what I wanted to say?
 
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samuelmorris said:
Half the time is an exaggeration, i'd say 85%+ of the time crossfire works well in modern games, there are only a few recent examples of it not functioning properly.
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85%+ of big name titles that you see get reviewed on sites like [H] ? Yea I guess.

I'd say half the time is closer to reality when you consider titles that don't get mainstream attention. This applies to both SLI and crossfire. Review sites really like to paint a rosey picture when it comes to multi-GPU setups and tend to use games that are popular and tend to work. If you play nothing but these games, sure it's great. If you play a lot of more obscure games, then it's not as good as you might think.
 
Intel_Hydralisk said:
85%+ of big name titles that you see get reviewed on sites like [H] ? Yea I guess.

I'd say half the time is closer to reality when you consider titles that don't get mainstream attention. This applies to both SLI and crossfire. Review sites really like to paint a rosey picture when it comes to multi-GPU setups and tend to use games that are popular and tend to work. If you play nothing but these games, sure it's great. If you play a lot of more obscure games, then it's not as good as you might think.
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Sure, if you include all the games from the pre-Windows XP era that don't even need crossfire. You have to consider crossfire 'working' in the context where it's necessary. If you could get 60fps solidly with an 8400GS, crossfire not working is of no significance, hence the 85%+ figure I stated.

Also, rage didn't work in SLI for a long time either. Does it even run with SLI yet?

Therefore, the HD6990 loses at high resolutions against the GTX590?
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Well no, the opposite is true, and if you read my post correctly, you'll realise it backs that fact up.
 
samuelmorris said:
Sure, if you include all the games from the pre-Windows XP era that don't even need crossfire. You have to consider crossfire 'working' in the context where it's necessary. If you could get 60fps solidly with an 8400GS, crossfire not working is of no significance, hence the 85%+ figure I stated.
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I don't know how many games you play... but there are MANY MANY more games out there than the ones reviewed on websites for benchmarks. And they aren't all pre-windows XP era games. I was specifically referring to 'modern games'. A good number of them will not work with xfire / sli.
 
Let's start seeing some relevant examples then. Again, I did state 85%+, not 100%. You'll have to come up with an impressive list to prove what I said wrong.
 
samuelmorris said:
I can only think of one recent title (DEHR) that doesn't work properly in crossfire. Two if you count BF3 but with the latest updates that too seems to work OK.
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How does DEHR not work well in Crossfire? I played at 1920x1200 max everything and I was often getting framerates over 100. This was several months ago, but when I played it it seemed to be working for me.
 
Crossfire scaling is only about 20% in DEHR. Your frame rate is 100 because you run 1920x1200. I get a frame rate of about 50 because I have twice the pixels to render. With a single card, it only drops to 40-45.
 
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