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CrossfireX or SLI?

timmillwood

timmillwood

timmillwood

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18 Jun 2011
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223
Which is better ATI & CrossfireX or Nvidia & SLI?

Looking to spend no more than £150 per card, but the closer to £100 the better.

Also, I am not sure I quite understand CrossfireX and SLI, can you explain how to set it up, and how it works?
 
setup is pretty easy, you plug both card in and then attatch the cable between them. install drivers and make sure CF/SLI is setup in the cards control panel.
i think CF used to scale a bit better than SLI but i think the gap is a lot less now.
personally, unless you need 2 cards i would look at a £300 single card option.
 
Hi there,

At the moment - AMD scaling is slightly better with their 6000 series cards in crossfireX than current gen nvidia cards. In the £100-150 range the HD 6850 and 6870 are the best cards to run in crossfire arrangements since they are relatively cool/quiet/low-power usage cards that scale very well in crossfire. Cards like the HD 5850 and 5870 are often faster in single card arrangement but they don't scale quite as well in crossfire (and are also hotter - so more difficult to cool in a crossfire setup).

In this price range the best option from Nvidia is a pair of GTX 460 1GB or 560 cards.

As for the technology SLI and crossfire are pretty similar - you install two (or more) cards of the same type into a compatible motherboard. The cards share the work of rendering frames (cards render alternate frames or parts of frames) of the game so there is a significant performance advantage in games running a SLI/CF setup compared to running on a single card of the same type.

To get CF/SLI to work you need two cards of the same model number (although CF can allow the use of cards from the same family eg 5770 and 5750, but this isn't ideal) but brand/manufacturer of the card doesn't matter. You then need a motherboard that supports SLI/CF (whichever you will be using) and a power supply that can happily power these cards and the rest of the system at full load. You install the cards in the correct slots as indicated in the motherboard manual and install the CF/SLI bridges between the cards. You then load into windows, ensure that latest graphics drivers are installed, go into either AMD Catalyst control centre or Nvidia control panel and enable CF/SLI in the options. You can then run your games (so long as the drivers have SLI/CF profiles set up) and see a decent performance improvement compared to a single card. Usually SLI/CF scaling gets better as you increase the resolution. Also to note, when running two cards in SLI/CF the graphics memory of each card is mirrored - so two 1GB VRAM cards (like the HD 6870) run in CF will only have a total usable graphics memory of 1GB, not 2GB.
 
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oversimplified version:
Both are just names of when you use 2 cards together.

SLI is Nvidia's name for it.
eg, you could use to GTX 560's and that would be SLI

Crossfire/ xfire is ATI/AMD's name.
eg, two 6870's would be xfire
 
SLI is the more rounded/polished of the 2.

TBH tho its generally best to buy the fastest single GPU you can for your money the only reasons to buy a multi GPU setup is in cases where:

The current top end single GPU is insufficent
2 mid-range cards are significantly faster than the current top end while cost a lot less.
 
Rroff said:
SLI is the more rounded/polished of the 2.

TBH tho its generally best to buy the fastest single GPU you can for your money the only reasons to buy a multi GPU setup is in cases where:

The current top end single GPU is insufficent
2 mid-range cards are significantly faster than the current top end while cost a lot less.
Click to expand...

or you already have 1 card and only the budget for another one rather than a better one, like i was.
a single card is generally going to give you less dips in the FPS. mine averages ok and doesnt do too bad at its max fps, but it does go down to less than 30fps quite often, whereas a single card wouldnt.
if you have a £300 budget then buy a £300 card and not 2 £150 in my opinion.
 
timmillwood said:
My reason for going CrossfireX / SLI is...
1) Seems like fun
2) spreads the cost
Click to expand...

it also increases heat and noise, and needs a more powerful psu, and like i said, although your average and max fps are good, unless you are buying this just to benchtest, you will be going into very low fps a lot of the time. a lot of games are not optimized for CF or SLI, just like they are not optimized for 6 cores, so its money for no real gains, just better bench scores.
 
1) Wouldn't describe it as fun, it's not even a challenge any more! That's not a complaint btw!

2) It certainly does spread the cost if you buy one now and get the other later.
 
The scaling of AMD CrossfireX is better than nVidia SLI in the current generation, i.e. AMD 6000 series vs nVidia Fermi.

However it is not a good idea to do SLI/CF with 1GB cards because more and more games can use more than 1GB and the GPU power is impaired by this. When you turn down AA and other expensive graphics settings of games you don't really need GPU power from two cards.
 
paradisiac said:
or you already have 1 card and only the budget for another one rather than a better one, like i was.
a single card is generally going to give you less dips in the FPS. mine averages ok and doesnt do too bad at its max fps, but it does go down to less than 30fps quite often, whereas a single card wouldnt.
if you have a £300 budget then buy a £300 card and not 2 £150 in my opinion.
Click to expand...

The lower fps minimum with multi GPU is the exception to the rule & can be down to driver overhead at resolutions that are a bit to low for the multi GPU & the CPU was near bottleneck even with the single GPU in a particular game at a given resolution or in the rare case that a particular game just does not handle multi GPU well for whatever reason at the time.

Also some set-ups just flat out have issues.
 
Final8y said:
The lower fps minimum with multi GPU is the exception to the rule & can be down to driver overhead at resolutions that are a bit to low for the multi GPU & the CPU was near bottleneck even with the single GPU in a particular game at a given resolution or in the rare case that a particular game just does not handle multi GPU well for whatever reason at the time.

Also some set-ups just flat out have issues.
Click to expand...

most of my parts sold, so hopefully my G620 will be replaced with a 2500k next week so will see if that helps, but my X2 250 OC'd and my X2 555 unlocked to ti-core @ 3.8GHz also suffered from the dipping into min fps far too often.
 
paradisiac said:
it also increases heat and noise, and needs a more powerful psu, and like i said, although your average and max fps are good, unless you are buying this just to benchtest, you will be going into very low fps a lot of the time. a lot of games are not optimized for CF or SLI, just like they are not optimized for 6 cores, so its money for no real gains, just better bench scores.
Click to expand...

I wouldn't agree wholeheartedly with that sentiment. SLI/Xfire is hardly for better bench scores alone. Improvements in gaming, especially at higher resolutions will see huge improvements, more often than not at avg, max and min fps.

That isn't to say everyone should go for a dual card setup, there are some seriously powerful single cards out there which can handle most anything but that can always be improved upon by doubling up.

If you are gaming at say 1680x1050 then a good single card will suffice. However if you have a 30" monitor you will generally get better performance from a 2nd tier dual card setup than a top tier, single card

Sure there are games that are not the best at utilising dual card setups but for the most part I would say SLI/Xfire is certainly worth it, especially for those who are looking for a boost but do not have the budget for a single flagship card. It all depends on your individual setup and needs.
 
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