SLI vs CF with multi monitor gaming.

[kompis]

Hey there fellow enthusiasts! I have enjoyed this site but not I am in need of assistance and I guess its time to stop lurking.

I'm building a new rig in July, I have been planning it for a while and while I have all the other parts sorted out I simply can't make up my mind regarding the GPU's.
I will be playing on 3x U2412HM's at 5760x1200.

I have always liked AMD graphics dating back to the ATI times and have never had issues with them. I was originally settled on 7950 Crossfire but I have heard way too many people complain about issues with 7 series cards, both in general and specifically with Crossfire and/or Eyefinity.
Then after seeing what a performer the GTX 670 is I started leaning towards going SLI with a pair of them.

However there a few things I'm unsure about that are holding me back. First of all the 3GB on the 7950 versus the 2GB on the 670, while VRAM may not be much of an issue with standard resolutions I fear it may hold me back at 5760 and I intend to keep this setup for atleast 2 years. Then there is the issue of price, CF will cost me 200$ LESS than the SLI alternative. I'm also concerned about temperatures as it gets quite hot in this room during summer and the AC isn't always on so the cooler running the card the better (with some OCing at that). My final concern is how in general Eyefinity compares to Surround in terms of ease of use and how well it "plays" so to speak with games.

I know I'm new here and everything but this issue has really been driving me nuts lately and I would very much appreciate any feedback, especially from people who have firsthand experience with either setup!

 

[Aquinus]

A lot of people swear by the nVidia cards, but in multi-gpu/multi-monitor gaming you really will want that extra video ram because the extra-wide resolution is going to fill up vram really quickly. Also keep in mind that SLI and Crossfire doesn't add gpu memory between cards, it's duplicated so you really still only have 3gb to use even if you have 3 GPUs.

I completely understand what you mean though, I've had amazing luck with ATi and AMD which is why I tend to stay away from nVidia. All the nVidia cards I've had in the past have either died or run really hot. This isn't the case really anymore with 600-series card, but as you said most if not all 670s are 2gb. I really think 3gb cards for what you will be doing would be wise.

 

[kompis]

No CF users here who would care to chime in? The VRAM difference is the main thing holding me back from committing to the 670's.

 

[bbmarley]

having 6950 crossfire and running eyefinity
its easy to setup
yes the top card will run hotter then bottom [will be the same as nvidia]
gaming is great and will take some getting use to

couple things i dont like
1-crossfire does not work in windowed mode
2-when using extended having a game on monitor 1 then open up a flash website like youtube on monitor 2 the gfx card gpu clock lowers causing fps drop in game

reason 2 is prob why my next card will be nvidia

 

[Completely Bonkers]

How much memory do you need? It will all depend on the "game engine". If you do the math, the amount of memory needed to hold the framebuffer(s) is TINY, even at 5760x1200. I have not been able to find out how a typical game engine and the graphic settings will impact the relative balance of memory needed for textures, for geometry mapping, and for the z-buffers and AA passes.

Maybe you can track something down on a website, where someone has analysed memory utilisation for a typical game engine... but I didnt find anything!

However, look here: http://www.techpowerup.com/forums/showthread.php?t=142867 and perhaps play with some of those memory logging tools and test it out yourself. See how much more memory is being used on one of your existing cards as you scale resolution.

 

[kompis]

I'm not even sure how much memory I need. I'm fine with 4xAA and even no AA if that's what it takes to get a nice smooth framerate. I could live with a little less texture modding my Skyrim for example but I just don't want to handicap myself right off the bat. This is actually driving me nuts since I could get 7950's that would do 1ghz and have 3GB VRAM for less money but I fear running into driver issues.

 

[Completely Bonkers]

OK, out of curiosity I just downloaded memory analyser from ATI http://www.amd.com/us/products/workstation/graphics/tools/Pages/tools.aspx (bottom of page)

Then I loaded up Team Fortress 2 and played (the training map, first room only) at various resolutions with default graphic settings. Here are the results:

1. 640x480 = 300,000 pixels, Fraps FPS 90, ATI Peak Memory 80MB (Index 100,100,100)
2. 800x600 = 480,000 pixels, Fraps FPS 70, ATI Peak Memory 90MB (Index 156, 77,112)
3. 1280x1024 = 1,300,000 px, Fraps FPS 35, ATI Peak Memory 100MB (Index 427, 39,125)
2. 1600x1200 = 1,900,000 px, Fraps FPS 25, ATI Peak Memory 120MB (Index 625, 28,150)

Although this is incredible unscientific, and taking rough averages, then the conclusion is as follows.

If you increase resolution (number of pixels) by a factor of 4.0x, then FPS goes down by a factor of 2.5x (worse than halves), but the memory demand increases by only 1.30x.

So, in Team Fortress 2, if you go from a single screen to a three screen setup (factor of 3.0x), the memory demand increases by less than 1.30x, ie less than 30%. If I was running 4800x1200 then I would probably need 160MB and my FPS would be 12.

YOUR MILEAGE MIGHT VARY!

 

[kompis]

But what about scenarios like large maps (BF3 for example even though I have no interest in it) or an open world game like Skyrim or GTA?
I'm also aware that the actual framebuffer is tiny but you have to consider high res textures and possibly mods as well.

 

[Completely Bonkers]

The point we are discussing here (in case you forgot!) is: does a 3 screen set up need a lot more RAM than a 1 screen set up? Naiively, does it need 3x as much vRAM? The answer is NO.

The question whether 2GB or 3GB is better for new games with large maps and multiple large textures is not what we were discussing. Just go to ANY BENCHMARK REVIEW to get the data for that. What you wanted to know what how does 5760x1200 compare to 1920x1200 in terms of memory demand. Answer: you need somewhere between (minimum 100MB more and 20% more vRAM). If 1GB was enough for 1920x1200 then somewhere between 1.1GB and 1.2GB is needed for 3 screens. If however the game needed 1.5GB then you will need somewhere between 1.6GB and 1.8GB for 3 screens.

Go look at reviews. If you see a major performance difference between 2GB and 3GB cards on the games you want to run, get the 3GB cards. If here is no noticable difference, then GET EITHER, depending on features and budget

 

[kompis]

One of the problems is I play many different games and this is not a BF3 or Skyrim system or what have you. I'm well aware that 3x the monitors doesn't mean I would need 3x the VRAM. I wanted to know if 2GB is enough VRAM for 5760x1200 for basically every game out there right now if you exclude extensive modding.

Also while browsing the Windforce 670 review and the 7970 GE reviews I noticed the 670 didn't work at triple monitor res in Hard Reset, CIV4 and I think there was one other game which I forgot. Is that due to some driver issue or what?

 

[EarthDog]

Havent tests shown, even at a triple monitor res, that 2GB is plenty now (even for BF3?). I mean if it was a problem wouldnt reviews that use multimonitors show the 670/680 get crushed by its ATI counterparts? My memory may be off, but.. thats what I recall...

 

[cadaveca]

Havent tests shown, even at a triple monitor res, that 2GB is plenty now (even for BF3?). I mean if it was a problem wouldnt reviews that use multimonitors show the 670/680 get crushed by its ATI counterparts? My memory may be off, but.. thats what I recall...

BF3 is not a good example. It will dynamically change detail settings according to GPU performance when "ultra" detail levels are selected.

In other words, the rendering load from card to card is NOT similar.

The idea behind your comment though, for sure.

Of course, image quality also differs between cards anyway, so there is something to be said about the relevancy of such compares.

 

[mastrdrver]

One of the problems is I play many different games and this is not a BF3 or Skyrim system or what have you. I'm well aware that 3x the monitors doesn't mean I would need 3x the VRAM. I wanted to know if 2GB is enough VRAM for 5760x1200 for basically every game out there right now if you exclude extensive modding.

Also while browsing the Windforce 670 review and the 7970 GE reviews I noticed the 670 didn't work at triple monitor res in Hard Reset, CIV4 and I think there was one other game which I forgot. Is that due to some driver issue or what?

Yes.

 

[EarthDog]

BF3 is not a good example. It will dynamically change detail settings according to GPU performance when "ultra" detail levels are selected.

In other words, the rendering load from card to card is NOT similar.

The idea behind your comment though, for sure.

Of course, image quality also differs between cards anyway, so there is something to be said about the relevancy of such compares.

Ive heard that once before here, asked for proof, but have yet to see any. Would you happen to have a link supporting that assertion?

In fact, due to that statement, I started a thread at OCF while back.. AND here... Nothing but proof it happens in another game, not BF3.

EDIT: I just realized I emailed someone at EA and Nvidia with no response. I will follow up again. I will look tonight when Im at home and follow up.

 

[cadaveca]

Ive heard that once before here, asked for proof, but have yet to see any. Would you happen to have a link supporting that assertion?

In fact, due to that statement, I started a thread at OCF while back.. AND here... Nothing but proof it happens in another game, not BF3.

EDIT: I just realized I emailed someone at EA and Nvidia with no response. I will follow up again. I will look tonight when Im at home and follow up.

Hrm, you know, I'm not sure. I could be mistaken, for sure. HOwever, I think you might have mor eluck contacting Patrick Lui @ DICE, than two companies that didn't make the game, and ewrgo, might now know the answer.

The latest update also seems to ahve changed teh game a fair bit, textures are different and such, so even if that was teh case before, it might not be now.

Anyway, I seem to remember something about compute and tesselation, but it's all kinda foggy. I didn't know you posed this question before...

 

[EarthDog]

hahahahahahahahaha... you got it.. And thank you.

 

[cadaveca]

hahahahahahahahaha... you got it.. And thank you.

WEll, you know, there's no denying that BF3 uses more tha n1 GB wit hcards with more than 1 GB of vram, and it uses LESS tha n1 GB on cards that have less.

How, why, wtf is going on, psh..I dunno wtf is going on.

Anyway, back to the OP, I'd not bother with AMD and both Eyefinity and Crossfire right now, IMHO.


I haven't had the chance to try nVidia's current cards in multi-GPU/Multi-monitor, but what I do know is that for my own rig, with 3x 6950 2 GB cards, and three U2412M, or whatever monitors i got(lulz, cannot remember that, even), driver issues are plentiful, and the only drivers that work for me is the 12.3 and 11.11c releases. All the rest are broken for three cards.


I'd love to hear from nV users though..I am seriously seriously considering a GTX690 to replace my AMD cards.

 

[Crap Daddy]

I'd love to hear from nV users though..I am seriously seriously considering a GTX690 to replace my AMD cards.

Here's a guy over at xtremesys who switched from 7970 crossfire to NV:

http://www.xtremesystems.org/forums...0-s-replacing-2x-7970-s&p=5111006#post5111006

 

[kompis]

Appreciate all the replies fellas they have definitely helped steer me in the right direction which would be NV in this case. I also very much enjoyed the 670 Windforce review here, it looks like a cool, quiet and fast card.

 

[radrok]

I'd love to hear from nV users though..I am seriously seriously considering a GTX690 to replace my AMD cards.

2x670 4GB over the 690, Dave, I tell you this because you play with very high resolutions and 2GB is going to hold you back.

Even though the 690 is just fricking sexy.