nVidia Dual GPU Cards

[MiRai]

We usually recommend that people don't purchase dual GPU cards or run SLI for multiboxing because it can hurt
performance. Browsing the Anandtech forums today I stumbled upon a thread about nVidia dual GPU cards and the
fact that the internal SLI can be turned off so both GPUs run separate.

http://forums.anandtech.com/showthread.php?t=2159007

Replies #6, #7, and #11 confirm:

Owning a 590, yes you can easily just check the box in the control panel that turns off SLI mode.

You then have the option of forcing physx to use the second gpu, or allowing the driver to determine which GPU gets used for physx.

So it is extremely easy to turn off SLI if you decided you don't want dual cards running.
Yes you can "disable SLI" with a dual GPU Nvidia card. The Nvidia Control Panel does not call it SLI if it is one physical card with two GPUs, but rather something like "multiple GPU acceleration" or something like that.
Yes, there is a "Disable multi-GPU mode" option in the "Configure Multi-GPU, PhysX, Surround" section of the Nvidia Control Panel.

[Ualaa]

That's neat.

Theoretically the 590 will run better than the 580 in some applications.
(I'm assuming 580 is the single version, and 590 is the two 580's on one physical card.)

[Noids]

The 295GTX also has this option in the Nvidia control panel. Surprisingly (or not, knowing how WoW and multiboxing goes with multi GPU) my fps improved by 15-20% across the board when I switched multiGPU off on my 295GTX. It was this realisation that drove me to purchase the 580GTX when it was initially released.

I haven't done much reading on the 590 to be honest. Is it actually 2 x 580 spec chips on the one card or 2 x 570s similar to how the 295 was 2 x 275s rather than 2 x 285s?

If it is the 2 x 570s, I would still recommend getting a single 580 over the 590 GTX for WoW multiboxing.

[confusedtx5]

The cores on a GTX590 are the same as a GTX580 BUT they are downclocked versions.
2x GTX580s in SLI will beat out a single GTX590 in SLI/multigpu.
NVIDIAs excuse was to reduce the power consumption and to keep the heat generated at a slightly more respectable level.

edit (linky): http://www.fudzilla.com/graphics/item/22109-nvidia-downclocks-the-gtx-590
(http://www.fudzilla.com/graphics/item/22109-nvidia-downclocks-the-gtx-590)

[Sajuuk]

I don't remember having any issue running on different GPUs on dual gpu cards when I had my 9800GX2s.

[Sam DeathWalker]

I would not get 2 GPU if you only have one monitor though but I guess if you run 4 tiled on one monitor and 1 main on another monitor, getting 2 GPU if your card allows duel output, makes some sense.



Still one gpu with 2G ram is going to be better then two gpu with 1G ram each I thinks, as I would assume that neither of the two gpu's can access the others ram space.

[Sajuuk]

I would not get 2 GPU if you only have one monitor though but I guess if you run 4 tiled on one monitor and 1 main on another monitor, getting 2 GPU if your card allows duel output, makes some sense.



Still one gpu with 2G ram is going to be better then two gpu with 1G ram each I thinks, as I would assume that neither of the two gpu's can access the others ram space.

What the hell are you spouting? Stop it, you'll confuse the masses.

Things to do with multiple gpus, using one/two screens.
Assuming five clones, run three clones on GPU1 and two on GPU2. BAM. Overall performance increase since the load is distributed. You don't need one monitor for each output on the cards. The card/GPUs will be detected just fine.

[Sam DeathWalker]

Assuming five clones, run three clones on GPU1 and two on GPU2. BAM. Overall performance increase since the load is distributed


What you mean is run 3 clones with 1G of video memory and 2 clones with 1G of video memory. Then combine the output of the two GPU's and send to a single monitor?

I don't think thats more bang for the buck (of coruse you get a better single gpu then a two gpu card for the same price) then getting a better gpu with 2G of memory and run 5 clones with it (load is also distributed with one gpu its all distributed to the one gpu ...).


GPU speed only effects the quality you can run the game at its the video ram that limits your fps (assuming you are not running the game at effects greater then what your gpu can handle). You don't need full shadows and some other usless effects in which case you really dont need more then 460 or so. Lack of full effects is a lot less bothersome then lack of fps. Thats why I run only one client main on my main computer (full effects) and the others on other monitors with way less effects.

The only time I can see using 2 gpus is if you have two monitors to one computer and run 1 on one monitor and 4 on the other (tiled).

Not to say one way is 100 times better then the other we are arguing over 5 percent differeneces if that. If you get a cheap deal on a 2 gpu card then go for it. You don't pay 10 percent more to get a 5 percent increase.

[Sajuuk]

What you mean is run 3 clones with 1G of video memory and 2 clones with 1G of video memory. Then combine the output of the two GPU's and send to a single monitor?
Single, Dual, Tri, Quad, Penta scheme monitors IT DOESN'T MATTER, OR HAS NEGLIGIBLE REAL WORLD IMPACT (unless you're running on XP for some reason, I remember the spanning desktops workaround for that.)


I don't think thats more bang for the buck (of coruse you get a better single gpu then a two gpu card for the same price) then getting a better gpu with 2G of memory and run 5 clones with it (load is also distributed with one gpu its all distributed to the one gpu ...).
Other considerations aside in the multi-vs-single gpu debate (power consumption, temperature, etc, two lesser gpus with 1gb of memory each working in tandem (in theory) perform better than one high-end gpu with 2gb of ram. Since workload is split between them, say, 2/5 and 3/5, that much ram is also freed up for various things 3/5 // 2/5 respectively. Issues with this will come up when we are rendering multiples of large areas (say 5x 3240x1920, something I did just fine with a 5850 (WITH 1GB OF RAM). NO ISSUES THERE. More headroom allowed by a card with 2GB of ram is fine and good, but does it translate into more performance? Not necessarily. Far as rendering large areas, I fairly sure you don't do that, what with your silly 26/36/whateverthehellyou'reboxingrightnow. For performance with your dated hardware you scale things down. We all do that for better performance.



GPU speed only effects the quality you can run the game at its the video ram that limits your fps (assuming you are not running the game at effects greater then what your gpu can handle). You don't need full shadows and some other usless effects in which case you really dont need more then 460 or so. Lack of full effects is a lot less bothersome then lack of fps. Thats why I run only one client main on my main computer (full effects) and the others on other monitors with way less effects.

You should know that we go for performance rather than "omgshinies" when we're boxing. Latency/FPS is important. GPU speed and ram are both important.


The only time I can see using 2 gpus is if you have two monitors to one computer and run 1 on one monitor and 4 on the other (tiled).

Shut up. Sometimes I think you're incredibly limited intellectually. Why in the world would I dedicate one gpu per monitor? Todays cards are powerful. They can handle putting things on multiple monitors. This is not 1986.



Not to say one way is 100 times better then the other we are arguing over 5 percent differeneces if that. If you get a cheap deal on a 2 gpu card then go for it. You don't pay 10 percent more to get a 5 percent increase.
There's more to getting a dual gpu card than just a 5ish percent increase. Form factors are one thing. Say I wanted to be really stupid and build a 25 boxing machine that would run things nicely - I would distribute the load. And in a limited space I would do that with dual-gpu cards.

[Sam DeathWalker]

25 boxing on one computer isnt what we were talking about. 10 Boxing is what we were.

You have no links to any of yur assertations.

http://www.techpowerup.com/reviews/HIS/Radeon_HD_6950/29.html

You seems to think that you will get double the performance with 2 gpu as you would with 1 gpu simplly because you are 5 boxing.

Most of the time the 2nd GPU seems to add like 30 percent increase, on single boxes.

You have a single buss. If you have to feed data to two GPU yur buss is twice as busy. Ya if all the data is avalable to both GPU's the instant they need the data for the next instruction you will get substaintial performance benifit but that just not going to happen at all in real world applications. Even a single GPU if all the data is available when needed will blaze though wow. It not how fast the GPU returnes the result of that instruction, its how fast that the data is available for that instruction after the last instruction is completed. And having two gpus dosnt help that much at all.


If the gpu's cannot access the other gpu memory space you have to load the SAME TEXTURE into VIDEO RAM TWICE. I don't think they would specify it as 2X1G if the gpu's can access the others memeory space. With two cards we know for sure that one gpu cannot accress the other gpu's memory space. If you have to load the same texture to video ram twice you are mitigating any potential benifits of two gpus.

If the gpus CAN access the total memory space then one will be waiting while the other is useing the texture if they both need the same one.

And "distribution" of 3 on one vs 2 on the other means that one gpu is working 1.5X the other meaning that one gpu is doing nothing 1/3 of the time.



The 6970 according to that artical is 370

The 5970 is 589

No doubt prices are outdated but should still be relitivly equal. You will not get 589/370 more performace from the duel GPU under any set of conditions. Note that the single gpu has higher speed also.

Look at the performance per dollar graph .... The single GPU is 100, the duel GPU is 69. Higher is better ....




Just buy the cheapest 2G video card you can .... then spend the money you saved on system ram.

If we both have X dollars to spend and you buy a duel gpu and spend the rest on system ram and I buy a single gpu and spend the rest on system ram (and have more system ram then you do), my system will run 5-10 boxes of wow for sure better then yours. There is NO QUESTION about that. If you give any other advise you are 100percent wrong.

My junk systems are fine for 7 boxing on one computer cause I play in full screen and only stress my gpu as if I was playing one box ....


Lets say we ahve 800 to spend you spend 589 on the duel gpu and get 21G of system ram. Figure $10/1G for system ram.

I spend 370 on single gpu and get 43G of system ram.

My system will blow yours out of the water, assuming all the rest of both systems are equall.

"I be frag'en while you be lag'en" - SDW '11 (copywrite Sam Ferris 2011 all rights reserved)


LMAOROTFL

I ain't brag'en
but I be frag'en
while you be lag'en
and my epen be DRAGON!

LOLOL

[Sajuuk]

All your links are to ruddy benchmarks I don't care about because I'd like to think I'm talking mostly abstractions.


You seems to think that you will get double the performance with 2 gpu as you would with 1 gpu simplly because you are 5 boxing.
Not quite. By distributing the load between gpus you would get higher consistent performance across more clients than with one gpu. It might not be double normal performance. It might not be 25% higher. But assuming equivalent gpus you would better performance in high-intensity situations. Not having access to new cards/not multiboxing I myself can't test these things. It is my opinion.

Looking at wikipedia the PCIe v2 x16 bus is 16GB/s. With even a dual-gpu card I don't think that's going to be an issue. Now, I'm not certain of how bandwidth is affected by having multiple cards in multiple pcie slots, but I would say each card/slot should have the same bandwidth, depending on the motherboard. With a lesser motherboard those cards would be limited depending on specs.


If the gpu's cannot access the other gpu memory space you have to load the SAME TEXTURE into VIDEO RAM TWICE. I don't think they would specify it as 2X1G if the gpu's can access the others memeory space. With two cards we know for sure that one gpu cannot accress the other gpu's memory space. If you have to load the same texture to video ram twice you are mitigating any potential benifits of two gpus.

Looks like you're assuming that the application in use will check for textures already in use and reuse the already used textures (i.e caching). For all we know that behavior isn't there and I would bet it isn't. So sharing the same memory space doesn't do much except clutter it up. Now, with more ram there is more space to fill up, so textures could remain in memory longer.

In these situations when we are talking performance loss I think we are talking MINUTE losses. The bandwidth is there. The slowest part of the system is the storage drive/interface.


And "distribution" of 3 on one vs 2 on the other means that one gpu is working 1.5X the other meaning that one gpu is doing nothing 1/3 of the time.
So? You get better performance overall with leeway for higher load either now or in the future due to either textures/graphical needs increase or added clients.


Just buy the cheapest 2G video card you can .... then spend the money you saved on system ram.
That I won't argue.


"I be frag'en while you be lag'en" - SDW '11 (copywrite Sam Ferris 2011 all rights reserved)


LMAOROTFL

I ain't brag'en
but I be frag'en
while you be lag'en
and my epen be DRAGON!

LOLOL

Bugger off you. :p

[Vociferate]

I am taking sides with Sajuuk on this one.



"I be frag'en while you be lag'en" - SDW '11 (copywrite Sam Ferris 2011 all rights reserved)


LMAOROTFL

I ain't brag'en
but I be frag'en
while you be lag'en
and my epen be DRAGON!

LOLOL

Really?

.... REALLY?