Hello:
I am planning to setting up 3 monitors, 20"-30"-20".

To drive them I was told that I need 2 Video Cards, so I am considering getting 2 8800GTSs.

My question is, it would be nice to be able to SLI the 2 cards to run some games, but I read in some thread that in SLI it will only drive one monitor (the 30" ).

But when I go back to "work", I would like to turn SLI off so that again I can drive the 3 monitors again for multiple desktops.

Can this be done?

My original plan was to get 1 8800GTX for the 30" and gaming, and re-use my existing 7600 GT to drive the 2 20" monitors, but I get conflicting info on wheather I can run 2 different Graphic Cards on a single mobo. Some say no, some say only if they are from the same manufacturer.

Can anyone dispell this one too?

Thanks

There are a few issues here for answering:

1) SLI only works on 1 monitor, that is correct.

2) You CAN turn SLI on/off, but if I recall correctly it requires a reboot of your system and is a pain in the A$$. But if you don't mind the constant switching, then fine I suppose

3) To run 3 monitors, you do need 2 cards unless you get a Matrox TripleHead2Go....which is not cheap but does allow SLI to power the 3 monitors since it reads them as 1 big one. However, it does have a max resolution and that might not correspond to your 20-30-20.

4) you need the SAME card to run SLI, you can't mix and match. 2 8800GTS's or 2 7600GT's, etc. They HAVE to be the same for SLI. However.......(next point)

5) you can match DX9 and DX10 cards in a non-SLI manner, however you HAVE to be using Vista. HAVE to. WinXP won't allow it. So you can use an 8800GTS/GTX and a 7600GT for example in non-SLI, but you HAVE to do it with Vista. So you could use the GTS/GTX for the 30" and the 7600GT or whatever for the 20's in Vista

6) trying to game across 3 monitors is extremely difficult in this setup though. And you'll likely be underpowered by alot. Just something to keep in mind if you were contemplating that option.

Hope that helps clear a few things up for you.

I can turn SLi on/off via the Nvidia control panel withoutneeding to reboot or remove the Sli bridge, I don't know about DX9 & DX10 cards only working on Vista but I have tried a 7900GT together with a 7900GTO on XP and whilst they would not Sli I was able to run four monitors.

Skyguy:
Thanks for the great answers, I am surprised that you could actually figure out that I actually had some many questions ;-) I am still a bit confused over the SLI thing, so not even abe to ask questions the right way, but you got them all.

But see me comments below please.

That is why i am confused, Mousemonkey says otherwise . Why does there seem to be so little NVIDIA documentation on this. Or is it just me that cant find it?

I looked int to3Head but not what I want. I would like to have 3 diff displays, so that I can maximize the res in each window, and keep diff apps maxed in each.

uhmm mousemonkey answer, leads me to believe that if the cards are similar i might be able to do it in XP. I do have a spare 6200 TC, wonder if it will work. I could always buy another 7600 GT since they are rapidly comming down in price.

Edit: Never mind. Cant SLI 6200

I have no intention of gaming across 3 monitors. Just on the 30", and that is why I was planning on either a GTX or SLIing. I figure that to run games in that high resolution I will need lots of Gjuice.

It sure does, but after mousemonkey's answer, i will experiment with the 2 lower powered cards 1st on XP, before buying that GTX. the 30" monitor is pretty much gona kill the budget :-(

1) Yes, I don't wish to contradict Monkey's info.....I *thought* switching between SLI required a system restart. I used to run SLI, but it's been awhile and I can't remember for sure. I know it can be enabled/disabled in the Nvidia Control Panel, but that was also in the Panel that was offered several drivers back. So things may have changed, that's entirely possible.

2) Also, regarding Monkey's info about 2 different cards, if you read it again, there is no conflict. What he said IS possible actually. He is running 2 DX9 cards (not the same cards though) in XP. That is definitely possible, not a problem. However, what I said what that you cannot run DX9 and DX10 together unless it's with Vista. XP will NOT let you mix and match DX9 and DX10 cards, but it will let you use different models of DX9, or diff models of DX10. BUT NOT both. So.....

-7600GT and 8800GTS in XP: NOPE.
-7600GT and 7900GTX in XP: YEP.
-7600GT and 8800GTS in Vista: YEP.
-7600GT and 790GTX in Vista: YEP.

See the difference? Only Vista will let you mix DX9 and DX10 card together in the same mobo. That's the bottom line. Hope that clarifies

BUT, and this is a big B-U-T........you cannot, cannot, cannot, use different models of cards together in SLI in any OS...not XP, not Vista. You cannot SLI a 7600GT and a 7900GTX, or ANY combination. They HAVE to be the same card. 2 7600GT's, 2 7900GTX's, etc. If, and I say IF, you can get hacked drivers.....you MIGHT get lucky, but I wouldn't risk that kind of money on "maybe", it's not worth it.

So, if you really need to go SLI, then get 2 8800GTS's, otherwise 2 lesser cards will suck BADLY. A single GTS beats 2 7900GTX's in SLI. To make SLI worth it, you have to go with very high end cards. Otherwise, if that'll kill your budget, then go with a single GTS to power the 30" and then add a 7600GT or other cheap card to power the other 2 monitors. Then that avoids ALL the problems. You get one good card to push the 30" with no SLI issues, no restarts, no bugs, no hassle. And you get the GT to power the other smaller screens, and it'll handle that no problem, there's no 3D gaming involved. And THEN you can use any OS you want and won't run into mixing issue like I described.

Now there's a win-win situation for you

Oh, and by the way.....I'm a Project Manager in real life, it's part of my job to cut through the "stuff" and find the underlying issues....which is why I could pull out all those questions you had from your post LOL


8)

By the way I'm an installation engineer, you know one of the guy's who sort out the project managers f**k ups and make everything work the way the client wanted it to.

By the way I'm an installation engineer, you know one of the guy's who sort out the project managers f**k ups and make everything work the way the client wanted it to.

Well if we are going to brag, then i am a consultant, you know, the ones that go into f*&%ed up situations and make money by prolonging the problem ;-)

Kidding aside, thank you both for helping out on this.

LOL....nice. You both are hilarious.

Even better: I work for the government.....they make a career of getting everyone and their brother to approve every little thing I do, give me all of the responsibility but none of the authority to actually DO my job, then blame me when it all goes sideways, even though I told them it was gonna happen if they didn't listen to me.

Can't win

So again thanks for the help.

Based on the info I decided to buy a 2nd XFX 7600 GT. I will SLI it to get a bit better performance for gaming and to drive the 30" monitor I am about to buy.

This is what I want to spend for now.

I decided not to get a 8800, because, I rather wait for DX10 games, and better Vista stability. By then I will get a much better deal on those additional 20" monitors and DX10 cards for the money. Prob only 6 months but I think that will make a big diff in price\performance.

If you are curious thake a look at the rest of the gear I bought in my Yahoo Photo:

http://new.photos.yahoo.com/speedy [...] 01052420/0