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1X 4Gb Gpu Or 2X 2Gb Gpus?


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#1 AnchisesGamer

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Posted 27 November 2012 - 08:03 PM

which would be better?

#2 Sen

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Posted 27 November 2012 - 08:26 PM

2 x 2Gb = 2Gb. The memory does not "stack".

To reiterate this so there is no confusion, you do not get 4 Gb running 2 x 2Gb cards.

This does NOT mean that 2 cards will not outperform the one card, but as you'e given no model numbers, it's impossible to say 100%.

#3 Catamount

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Posted 27 November 2012 - 08:27 PM

On paper, 1 4GB GPU, in practice, well... 1 4GB GPU, but not for the reason you may think.

You see, if you use two 2GB GPUs, you don't get the memory of both. Crossfire and SLI only use the framebuffer of the master card, so for your two 2GB cards, you get... 2GB. However, that's not really an issue. In most gaming situations, even 1GB is more than enough (basically, it's more than enough for 1080P for the foreseeable future), so it's highly doubtful that the difference between 2GB and 4GB will ever be meaningful withing the lifetime of the card(s). That said, you should always, always, always shoot for one powerful card over two slower ones. It's easier to wire for, the power draw is better, and most importantly, you don't have to deal with microstutter.

I wouldn't go as far as to say avoid Crossfire and SLI -including dual-GPU cards- at all costs, but it's not far off. The tradeoffs are big, and MS almost entirely overrides the performance advantage. Two cards are not meaningfully more responsive than one running at half the framerate; benchmarks might tell you you're going faster, but the playability will not drastically increase, because the increased latency keeps you from getting any increased responsiveness. The only time I'd recommend getting two cards at all is if it's impossible to get one that's powerful enough to suit your needs. Also, even getting one card, there's really no need to get a 4GB GPU, so if a model with less memory is around for the same performance, save the money and energy use and just get a smaller frame buffer (unless you plan on running, like, 3 2560x1600 monitors)

Edited by Catamount, 27 November 2012 - 08:29 PM.


#4 Sen

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Posted 27 November 2012 - 08:39 PM

Actually scaling on crossfire is fairly substantial. That's not to say that any card with 4Gb wouldn't beat. . say. . a pair of 6970s, but it REALLY depends on the cards.

Ease of setup, the higher powered single card is the win.

And. . wtf is microstutter? are we back on the 9.x Drivers? >.> I haven't microstutter since Burning Crusade ;D

#5 YellowDragon

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Posted 27 November 2012 - 09:58 PM

GPU memory does not stack with crossfire or dli configuration you only get the gpu vram of the master card which in the case of dual 2gb card is 2gb. Though unused vram provide no net benefit to fps unless you are reaching the full capacity of the vram. For instance most games at 1080p will never hit that 2gb frame buffer so a 4gb card would be worthless in a single monitor setup though if you are running 3d surround you would need more vram to drive multiple displays. What does matter in terms of fps on a single monitor is the GPU in the card and the speed its running at. I would recommend one powerful card over two weaker cards since few games are properly optimized for multi gpu setups. however if you have the cash and you drop in the highest end video card you can find and you want more power feel free to drop in another if you wish lol.

#6 RFMarine

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Posted 27 November 2012 - 10:01 PM

usually video card memory size is a poor indicator of performance.

if you are old enough you may remember the 512mb geforce 9800gt which totally outclasses the 1 mb geforce 9400


a noob friendly rule of thumb way of finding out which GPU to buy is to simply set a budget, get several models within that budget and google for benchmarks. the faster the benchmark usually the faster the card

Edited by RFMarine, 27 November 2012 - 10:02 PM.


#7 DV McKenna

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Posted 28 November 2012 - 09:24 AM

TLDR Version

Single - Dual Monitor gaming = 2GB
Tri Monitor + = 4GB to be on the safe side.

#8 Catamount

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Posted 28 November 2012 - 10:22 AM

View PostSen, on 27 November 2012 - 08:39 PM, said:

Actually scaling on crossfire is fairly substantial. That's not to say that any card with 4Gb wouldn't beat. . say. . a pair of 6970s, but it REALLY depends on the cards.

Ease of setup, the higher powered single card is the win.

And. . wtf is microstutter? are we back on the 9.x Drivers? >.> I haven't microstutter since Burning Crusade ;D


I'm afraid you've been misinformed. Microstutter has gone nowhere. SLI doesn't suffer it as badly as Crossfire (demonstrated here), but it also doesn't scale as well (~60% for 2 cards, instead of ~100%), so you get the same almost meaningless performance increase. If all you want to do is watch benchmarks play, then sure, at 60fps it's reasonably smooth, but the input lag introduced still makes the game play like it's going at 40fps, which makes having the second card almost pointless. That's why a couple days ago I finally traded my two 5770s for a single heavily OCed 5850; I lost about 5% performance (as measured by 3dMark11), but basically doubled the actual responsiveness of games, even at higher fps. Same fps, substantial upgrade. I made a BIG mistake not just paying the $100 and getting a 5870 instead of two 5770s when I built that comptuer, but oh well, live and learn.

At lower fps microstutter gets so bad, it even visibly chunks video. Run 3dMark or Heaven, and get those two Crossfired cards down to 30fps or less, and then compare them to a single card getting the same fps. The single card will look like it's going twice as fast because of MS.


Here's BF3 suffering MS at 30fps



Here's a more visible example




Past 40-50fps (that number purely from my own experience, it might vary for you), non-interactive video appears to stop suffering MS, but input lag stays bad. Again, this is the "responsiveness" of games, and it's something that, sadly, can't be demonstrated with a youtube video. It's also something you get "used to" with a Crossfire/SLI system, or at least I did playing with two 5770s for almost 3 years, but that's like saying you get "used to" low fps. It's still a huge difference moving to a single-GPU system. Moving to playing a 149kph Jenner with a single faster GPU vs two slower ones for the same framerate was probably the best thing I never did for MWO.


As an odd caveat to all of this, though, 3 or 4 GPUs (tri/quad xfire/SLI) do not suffer this problem nearly as badly, barely at all, in fact. The above Tom's Hardware link shows that. Why? I have no idea. Maybe somehow having more GPUs makes it more likely that one of them will finish the frame at the proper interval, or something, but it's more likely that I'm just talking out of my *** there. The why goes well beyond this poor bio major's knowledge of computing, I just know it does. Still, getting 3 or 4 GPUs is a complex and expensive proposition when one can just get one fast GPU and avoid all this headache altogether.

Edited by Catamount, 28 November 2012 - 10:26 AM.


#9 Hakkukakt

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Posted 28 November 2012 - 11:25 PM

hello ... just for exemple ... on tri screen 27" 5880x1080 no 3D ... MWO use 1.5 Go Vram on my GTX680 4Go ...

so if you often update your CG ... go for a 2 Go ... if you will take for a long road in futur .... go for 4 Go ....

#10 DegeneratePervert

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Posted 28 November 2012 - 11:26 PM

Gonna go ahead and weigh-in here. The single 4GB card will generally give you fewer problems than two 2GB cards, since you always get the same performance and don't have to rely on crossifre/sli drivers. As it has been mentioned before, the memory pool of cards in sli/crossfire does not stack.

#11 WM Xitomatl

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Posted 14 August 2013 - 01:57 PM

View PostHakkukakt, on 28 November 2012 - 11:25 PM, said:

hello ... just for exemple ... on tri screen 27" 5880x1080 no 3D ... MWO use 1.5 Go Vram on my GTX680 4Go ...

so if you often update your CG ... go for a 2 Go ... if you will take for a long road in futur .... go for 4 Go ....


THANK YOU for sharing this! That's exactly what I needed to know. I am planning on getting 2 more monitors for my setup and need to get a card to handle that. I've been toying with 2gb vs 4gb GTX680.

Can tell us the frame rates you've been getting with a single GTX680 in 5880x1080, and with what settings? I'm hoping to play in maxed out settings and need to know if one GTX680 is good enough for that.

#12 DV McKenna

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Posted 14 August 2013 - 02:01 PM

View PostXitomatl, on 14 August 2013 - 01:57 PM, said:


THANK YOU for sharing this! That's exactly what I needed to know. I am planning on getting 2 more monitors for my setup and need to get a card to handle that. I've been toying with 2gb vs 4gb GTX680.

Can tell us the frame rates you've been getting with a single GTX680 in 5880x1080, and with what settings? I'm hoping to play in maxed out settings and need to know if one GTX680 is good enough for that.


Depends entirely on teh Frame rates you deem acceptable.

My 4GB 670 FTW edition would play at 30-50 FPS depending on what was going on, the problem is no single card will provide stable FPS at those resolutions sans a GTX Titan/ 780 (possibly)
But then getting 2 won't help with no SLI/Crossfire support.

Reach for the best single card you can afford would be my advice.
If you still need a touch more performance for tri screen then you have time to save up until we get support for 2 GPU's.

But you'll need a strong CPU to push this.

Edited by DV McKenna, 14 August 2013 - 02:03 PM.


#13 Narcissistic Martyr

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Posted 14 August 2013 - 02:41 PM

Your necromatic might is strong.

I suggest starting a new thread to cover your eyefinity questions.

Regardless, the general rule of thumb is to buy the strongest single GPU you can afford.
Also, note that mwo doesn't use more than one GPU and is highly CPU bound. So the only systems I recall running eyefinity resolutions @ >30 fps have a titan and an i7 3820k or better. So you're talking a $2k+ system to pull it off. Worth it I imagine if you've got the money.

*

Edited by Narcissistic Martyr, 14 August 2013 - 02:45 PM.


#14 The Gunman

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Posted 15 August 2013 - 06:04 AM

View PostNarcissistic Martyr, on 14 August 2013 - 02:41 PM, said:

Also, note that mwo doesn't use more than one GPU and is highly CPU bound. So the only systems I recall running eyefinity resolutions @ >30 fps have a titan and an i7 3820k or better. So you're talking a $2k+ system to pull it off. Worth it I imagine if you've got the money.


I'm running 3-way Crossfired 7970s. I can ashore you that it does use all 3 GPUs.
Averaging 80fps at 5760x1080 with all settings maxed out.
Was totally worth the money,

#15 Catamount

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Posted 15 August 2013 - 07:13 AM

Whether MWO does or doesn't make use of SLI/Crossfire right at this instant should be immaterial to whether one should get such a setup for a gaming machine. First, support will be forthcoming one way or the other, and secondly, I seriously doubt most people coming here for advice are planning to build a $1000+ computer JUST to play MWO.

The relevant question is whether such a setup works well for *gaming*, not MWO. Now that Nvidia and AMD have both apparently solved the Microstutter problem (iirc the AMD driver is still beta, but functional), dual-GPU setups are suddenly a lot more compelling.

#16 Narcissistic Martyr

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Posted 15 August 2013 - 08:09 AM

View PostThe Gunman, on 15 August 2013 - 06:04 AM, said:


I'm running 3-way Crossfired 7970s. I can ashore you that it does use all 3 GPUs.
Averaging 80fps at 5760x1080 with all settings maxed out.
Was totally worth the money,


I stand corrected then.

#17 F lan Ker

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Posted 15 August 2013 - 08:57 AM

S!

AMD Catalyst 13.8 betas have fixed a lot of frame pacing that caused stuttering in CrossFire. Sure only works now in DX 10/11 but next patches improving in DX 9 too. On topic. I would take a fast single GPU with enough memory over a SLI/XFire due less problems with scaling or whatever. Will take a look on CrossFire after new AMD GPUs launch though and drivers for them are out.





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