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I've got an NVidia GeForce GTX 560 Ti, and want to add a third monitor to my system, but don't have the cash for another 500-series card for SLI. Given that, is there any advantage of adding a 200-series GTX, over say a GeForce 8800 or something?

I would have thought that the 2nd GPU would run everything that displays on the third monitor, but I have a similar (three monitors, one powerful card, one loser card) setup at work, and when I run furmark, it always maxes out the more powerful GPU no matter which monitor it's displaying on, and the loser GPU sits mostly idle. That makes me think now that upgrading the loser card has no benefit at all, but are there situations where that's not the case?

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7 Answers 7

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Of course only one card was maxing out the single GPU, you can't run SLI with different GPU cores.

Save up and get another GTX 560 Ti if you want to increase triple monitor 3D performance too. The only ability you get by adding a lower performance graphics card is the ability to use three monitors, that's it.

You can also use a slower card to perform the PhysX rendering. Also, if you use any CUDA-specific applications, you can offset them to one particular GPU if you needed to.


If your second GPU happens to be SLI-compatible with the first one (as with Crossfire, which only happens when they share the same GPU core), when SLI/Crossfire is enabled, your performance will be limited by the slower card (or rather, the card with a lower amount of memory or lower clock frequency).

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You can also use a slower card to perform the PhysX rendering. Also, if you use any CUDA-specific applications, you can offset them to one particular GPU if you needed to. –  Breakthrough Mar 7 '12 at 1:00
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I think what you posted as a comment is really the one situation where a second, lesser card is useful. I think getting the cheapest card possible or the same card is the sensible choice here –  Journeyman Geek Mar 7 '12 at 4:17
    
Good to know; I do software, so the CUDA is relevant, though since I've already got a 560 and I'm not starved for GPU power yet, I'll just go for the cheaper option until I need something bigger. –  Dax Fohl Mar 7 '12 at 13:02

I just purchased an Nvidia 610 PCI for my second video card. My monstrous Asus Nvidia 560 TI 448 core takes up too much room to add another PCI-E - a couple things I've learned from setting up multi-monitor and especially gaming in multi-monitor environments. First off - SLI wastes precious video RAM - until Nvidia figures out a way to utilize all the RAM and not just basically mirror the 2nd cards RAM, I will not go back to SLI. Not only that but, games and programs have increased compatibility issues with SLI. Just buy a powerful card to begin with - SLI is for the birds. My suggestion is to do what I'm doing - dedicate the primary video to one monitor - as to not waste precious video power on your primary applications/games. Purchase a second budget video card with a current chipset on it for the additional 1 to 2 monitors. I saw one suggestion to purchase an ATI card that can support 3 monitors - why in the world you'd want to gimp your card so hard is beyond me... my advice don't do it unless you need 4 monitors - then you could use the ATI to power the other 3.

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Your other option would be to sell your current GTX 560Ti to a friend and pick up an ATI Radeon HD 6970 2GB. It's more powerful than a single GTX 560Ti and it supports Eyefinity.

The NVidia cards, as you discovered will require two cards in order to display 3 monitors. The ATI Cards that support Eyefinity will allow you to run 3+ monitors on a single card. I picked up a 6970 last year for about $380 and must say that it does extremely well.

FROM NVIDIA'S WEBSITE FAQ

(http://www.geforce.com/Hardware/Technologies/sli/faq#c16)

Can I mix and match graphics cards that have different GPUs?

No. For example, an XXXGT cannot be paired with a XXXGTX in an SLI configuration.

Can I mix and match graphics cards from different manufacturers?

Using 180 or later graphics drivers, NVIDIA graphics cards from different manufacturers can be used together in an SLI configuration. For example, a GeForce XXXGT from manufacturer ABC can be matched with a GeForce XXXGT from manufacturer XYZ.

Can I mix and match graphics cards is one of them is overclocked by the manufacturer?

Yes. A GeForce XXXX GTX that is overclocked can be mixed with a standard clocked GeForce XXXX GTX.

ATI Card Mix & Match

Unlike NVidia, you can also mix and match different ATI GPUs when using CrossFire.

Here is a chart that lets you know which cards are compatible with different cards when talking about CrossFire.

enter image description here

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Not trying to be an Nvidia fanboy or anything, but in that chart you posted, notice how the only compatible configurations actually have the same GPU core (e.g. the 6850 and 6870). The only difference between models is the amount of memory and core speed. SLI works the same way - so long as you have the same GPU core, you can SLI the two cards (even if the amount of memory or clock speeds are different). –  Breakthrough Mar 7 '12 at 12:16
    
That being said, SLI or Crossfire, you will get the best performance using identical cards only. Furthermore, even in Crossfire, you're still limited to the slowest GPU (just like with SLI). The rendering algorithms are largely the same for both technologies, and indeed they should be - there's only a few scheduling algorithms you can use to evenly split a task up between two GPUs, and they simply don't work with mis-matched memory or clock speeds. –  Breakthrough Mar 7 '12 at 12:21
    
Granted, but the ability to use more than two monitors on a single card does speak volumes. Especially if your motherboard isn't sli compatible. However, one could always just add a second graphics card of any make/model and use additional monitors. For gaming/single desktop you're best to stick with sli or crossfire or single gpu eyefinity. –  kobaltz Mar 7 '12 at 14:22

Sometimes its not efficient to do dual SLI with different models of cards especially if they are from different series. From my knowledge the chipset and memory of the card has to be the same but the brand of it should not matter.

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It's sort of been said, but at least one important consideration was left out. Power. And of course I don't know anything about your CPU/peripheral power load. So, for you:

You'll need - at a minimum - an 800 watt PS. Much better that it be 1,000/1200. Assume handled.

Buy a second IDENTICAL card - 560 was it? Get a flexible dual SLI bridge Install the two identical GPUs in the first two PCIE nearest the CPU - PS connections of course Connect the "primary" monitor(s) to the closest GPU If one monitor, connect it to the DVI connector closest to the PCB. If two, connect any primary monitor to the DVI closest to the PCB Install your third GPU - it MUST be a DIFFERENT GPU than the SLI'd pair. Sure cheap is fine, but it needs to do whatever you ask of it. Run Physx, additional monitor(s), CUDA Your system may (Win7 will) see the SLI'd monitors and ask permission to make initial adjustments. Take it from there. Use whatever tuning utility - EVGA, MSI, etc - you like and you can dial in the 3 GPUs. Have experienced problems with EVGA Precision. I'm a long time EVGA guy with dual-SLI EVGA 460 SCs and a PNY 280 GTX in the third rail - about $350. If I've got the details wrong, will someone RSVP. Best of luck with your project.

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Don't think you all get what he is asking, He don't have money for another GTX560 and was wondering if a lower end card would work, yes it would work, but will the 3rd monitor actually use the lower end card? IDK, here is my situation and what I have noticed with ATI cards.

I have the HD5850 and everyone knows that its got a dual monitor flicker problem, so I went ahead a bought a HD6450 for a 2nd monitor, Works well and the monitor does not flicker anymore, Seems as if the HD6450 will use its Vram for certain things displayed on the 2nd screen like Win Areo, or media player, something that isn't in 3d. But the moment you have anything that uses the 3d clocks, I will default to the HD5850 (primary monitor), even if I move the application around to the 2nd screen, still 0 - 2% usage on the 6450 while the 5850 is at 99%. It will help performance out a little if you run 2d apps on the second monitor, but anything 3d still will effect the primary cards performance.

I think ATI - Nvidia should optimize their driver to take vantage on a secondary GPU for desktop usage, even with 3d apps, the secondary monitor should be used if the 3d app is on the 2nd monitor, Not saying that it should run SLI or crossfire, but the secondary card should render whatever it can if that monitor is attached to it. Primary card should render whatever is on the primary screen. sadly it don't work like that, some MMO's can force it somehow.

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If you don't want to SLI, but want to have 3 monitors, you can get a low level gpu, something around $100, and just use it for the 2 extra monitors, with the main monitor being hooked up to the 560ti. I currently have 1 monitor for my 560ti and 2 others on my gts 250. I have the 250 running PhysX. However, the only drawback to this is that there is no Eyefinity capability, for which you need 2 fairly high performance cards in SLI.

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