Running Graphics cards in SLI

[FBplmmr]

But what if you already own 2 video cards?

I was given 2 7800GTX's by someone who upgraded.  I would think buying an SLI capable board for my next build and using it would make sense then.
I currently have an old system with a 6800 AGP card.

[alskahawk]

But what if you already own 2 video cards?

I was given 2 7800GTX's by someone who upgraded.  I would think buying an SLI capable board for my next build and using it would make sense then.
I currently have an old system with a 6800 AGP card.

 Ok, as someone who owns two SLI systems. 2-8800GTXs one with 2-7950s Here is what you will need to SLI.

 Space, cooling and power are the three main problems with SLI. Two 7800GTX video cards will probably raise your temp by 10 degrees.

Case; 2-7800s should fit in a Antec 900 ($79) (my 8800s fit in a 900) Buy quality tho. Its difficult to cool a bad case.   Recomend full tower; Antec 1200 or a Cosmos(cooler master) 

Cooling; Water cooling not necessary. You can use a cpu fan/heatsink; 

Memory; Same as with any gaming computer today; 2 gig minimum

Motherboard. Research find a good solid MB. With two 768 GTX's (yesterdays technology) You won't need the newest hottest MB. Look for one that has 2-PCIx 16speed busses. Some of the first generation stuff had 16/8x combo speed. Not that you'll notice that much.

Power Supply; There is a wattage calculator at the Newegg.com website. 2-7800s I recomend a 750 watt minimum.   

Hard Drive; 10,000 rpm. 7200 rpm's are cheaper.

Operating System; I run XP. I also have Vista on a laptop. And since the service pack update have not had anymore problems with it. On a new system; I would probably go with Vista.

 

 

[sethipus]

...probably 42 amps min for SLI...

Given most household electrical circuits are connected at the main box in the house with 15 or 20 amp circuit breakers, perhaps someone wanting to run SLI ought to run extension cables from different parts of their house to their multi-input power supply just to be on the safe side, doncha think?  ;-)

As for the SLI, I agree with Krusty totally, waste of money for the most part. If you do get a single high end card make sure you've got enough amps on your 12V rail for it...

SLI is a waste of money for games that don't work well with it.  And for games that do, well, it's not a waste of money if it gives you what you want from it, and you can afford it.  There are plenty of games that get a good 50%-70% or higher framerate boost with SLI, and whether it's a waste of money or not depends on a person's means, desires, and what game they want to play.

Have you played Crysis?  It's a machine killer.  here's a part of an article showing benchmarks of Crysis showing performance with one card, two cards, and three cards, and the scaling is unbelievable.  They're seeing nearly like 80-90% scaling with those configurations in that game.  It would be hard to argue that that is a waste of money (in the context of video gaming, which in the grand scheme of things is all a waste of money, really).

[doc1kelley]

Given most household electrical circuits are connected at the main box in the house with 15 or 20 amp circuit breakers, perhaps someone wanting to run SLI ought to run extension cables from different parts of their house to their multi-input power supply just to be on the safe side, doncha think?  ;-)
SLI is a waste of money for games that don't work well with it.  And for games that do, well, it's not a waste of money if it gives you what you want from it, and you can afford it.  There are plenty of games that get a good 50%-70% or higher framerate boost with SLI, and whether it's a waste of money or not depends on a person's means, desires, and what game they want to play.

Have you played Crysis?  It's a machine killer.  here's a part of an article showing benchmarks of Crysis showing performance with one card, two cards, and three cards, and the scaling is unbelievable.  They're seeing nearly like 80-90% scaling with those configurations in that game.  It would be hard to argue that that is a waste of money (in the context of video gaming, which in the grand scheme of things is all a waste of money, really).

Just like some folks (like my wifey) would say that playing AH is a waste of money but I want to and I do.  I've run both Nvidia Sli (BFG 7800 GT OC cards) and now AMD/ATI Crossfire (Sapphire 3870 cards) and the most trouble free and best looking has been the crossfire configuration.  I could run three or four vid cards in my system but the two at X16 seem to be just fine.  However... I do NOT run that resource hog CCC but use Ray Adams ATI Tools instead and Omegadrivers.

All the Best...
     Jay
 awDoc1

[Chalenge]

Motherboard. Research find a good solid MB. With two 768 GTX's (yesterdays technology) You won't need the newest hottest MB. Look for one that has 2-PCIx 16speed busses. Some of the first generation stuff had 16/8x combo speed. Not that you'll notice that much.

x8 is quite likely all you will ever achieve in Sli unless you have one of the latest motherboards in PCIe 2.0 and even then most games wont need the extra benefit of x16 (FSX being the only exception that I am aware of). PCIe 2.0 is scaleable and backward compatible.

[alskahawk]

x8 is quite likely all you will ever achieve in Sli unless you have one of the latest motherboards in PCIe 2.0 and even then most games wont need the extra benefit of x16 (FSX being the only exception that I am aware of). PCIe 2.0 is scaleable and backward compatible.

 Most of the quality MB's produced in past year and a half are probably PCIe 2.o. I added that statement based on my 2 year old asus m2n SLI Deluxe 16/8x. But truthfully, I didn't notice any groundbreaking difference when I switched my 2 VC's to a XFX 2-16x MB. No doubt there is some difference but not that noticeable unless you run some sort of test on it. IMO.

 For those commenting on that SLI doesn't work with some games. I haven't run into any. I am limited (Damn AH!) to a handful of games. Maybe its some older games that have problems?

 Note; I probably overestimated how much 2-7800s will raise your Temp. Probably closer to 5 degrees. With my 8800s it was about 10 degrees.