Get Quad SLI Before It Is Hatched

I'd achieve similar heating output for my house through conventional means, i.e. an open log fire, or gas heating.

I'd achieve similar noise levels my moving nearer to an airport.

Seriously though, it is for the ultra-enthusiast, and by the time it is enabled and running smoothly, it will only be a few months away from being redundant by the next-gen cards.

The overall concept is of course sound - multi-core GPU - but the current implementation is clumsy as to be expected in the early days.

Avoid.

Although I have no experience with it, nor am I planning on using Quad-SLI, I feel it's pointless. Dual GPUs on single PCI-E slot are a pretty good idea, providing it's in a good price range.

Unfortunately the rendering power of these systems can't be fully realized until we rid ourselves of the massive CPU bottleneck. Seeing the Quad SLI systems fall behind the 'single' 7950 and occasionally the X1900XTX just screams a couple things: One being drivers; even though this is a solution that enthusiasts can purchase, it doesnt look to be a sane one other than to physcially look at four GPU's in your machine and smiling from the gratification.

Looking at that table of results, I feel as if Quad SLI loses more than it wins. However most of the victories for QSLI are only several frames a second. Are 4-7fps worth the $599 tag for another 7950? I cannot doubt that one of the GX2' is a great thing, however dual setup, and Quad SLI has some major growing pains and driver revisions before it comes out of this 'lab rat' stage of mere speculation and into the realm of producing acceptable results.

Granted I didnt comb the article with a magnifying glass....I only noticed Quad SLI taking a victory with FEAR and Oblivion, but again, not by more than a few frames. Which is where this leads us too; Much needed driver revisions and a large CPU bottleneck. Which we will have to wait and see how Quad core CPU's begin to aleviate this impact.

Like stated above though. By the time this is smoothed out, we'll see the next generation cards from our producers and of course a dual solution then will kill a Quad solution from now, without the extra $500.

[quote="DPolkowski"]What are your feelings on Quad SLI?

That it's STILL not "QUAD-SLi" , but SLi + SLi (only 2 cards in SLi communicating across the PCIe internal bridge).

And unless there's been a redesign it's not possible at the chip level.

Remember what SLi stands for as well. BTW, that SLi not SLI (unless they revived Scan Line Interleving as well). :tongue:

Other than that, nice for the people who need to power large panels, where really these setups shine for min fps (nice not to have to dumb down res and deal with interpolation).

Would've been nice to see Oblivion with AA, also interesting to see indoors where the plain GX2, GTX SLi and XTX beat the SLi+SLi.

BTW why a single XTX, why not an XTX+Xfire combo? IMO that would offer more interesting comparison, like Xbit Labs and a few other sites did.

Really, I just like the PSU they used for the testing. How cool would it be to bring your friends over and be like... "Yeah, this is my rig, my cold cathode tubs, my Crossfire X1900's, My C2D 6800 Exteme, my 4GB of XMS, my 4 Raptor X's and o yeah....a small refrigerator too.


           

Yeah, actually I really like PC P&C's stuff, but it is pricey, but for a build like this it's peanuts.  

Actually what I would've like to have seen would be this 'quad-sli' against a single Quadro of similar or lesser price in things like 3DSMax, Maya, SolidWorks, etc.

Wow. Quad SLI sucks. LOL. And I don't think more mature drivers are going to help the problem very much...

Great review guys! Thanks!

well i mean... sli wasn't really that great when it was in it's infancy was it?

You know, you'd think with all those GPUs, they could get some sort of HDR+AA thing going...

true that...

SLi doesn't change the hardware limitations.

Regardless of how many GPUs you added, they still need to either go through the ROPs twice or have the HDR or AA done in software (ala AOE3).

At this point what's nV's motivation to bring an ultra slow HDR+AA to market. If they did bring "some sort of HDR+AA" to market and it was 1/2 the speed of the ATi solution, what benifit would that offer above not having FP16HDR+AA , you still end up with ATi > nV, but you've wasted a ton of resources making essentially a hack/workaround that will never be able to be full FP16HDR+AA throughout.

I think people are going to have to look towards the next generation of nV for FP16 HDR+AA.

I <think> the newest drivers support HDR + 4x FSAA. I've got both enabled in Half Life: Episode 1.

I could be wrong though...

well i mean... sli wasn't really that great when it was in it's infancy was it?

It was ok... certainly better than quad SLI. But I see your point. :-)

It's not an issue of HDR+AA but FP16HDR+AA, it will never change that nV can't do FP16HDR+AA simultaneously, but they have 2 work around, 2 loops through ROPs with int8 second time around, or else 1/2 done in software like AOE3.

HL2 uses a mixed method of HDR that involves the option of integer HDR, nV can apply AA to int HDR, just not FP16 HDR in hardware.

There's a more comprehensive review of quad sli at Firingsquad that sheds quite a bit of light on the issue.

FS Quad Sli review

Basically, the driver overhead for quad sli holds performance back such that at lower resolutions, normal sli and even single cards perform better. As they indicate, it's only when using very high resolutions with 8xAA/16xAF that quad sli begins to shine. In fact, based on their benchmarks, the two quad setups have a 20-50% performance advantage over even the best normal sli or crossfire setups using such settings.

For instance, in HL2LC 2048x1536x32, 8xAA 16xAF
7900GX2 quad: 55.2 fps
7950GX2 quad: 54.8 fps
7900 GTX sli: 41.9 fps
x1900xtx cf: 37.1 fps

in Quake 4, same settings:
7900GX2 quad: 61.1 fps
7950GX2 quad: 60.8 fps
7900 GTX sli: 43 fps
x1900xtx cf: 35.6 fps

similar results for FEAR, Oblivion (bloom), etc.

With only 4xAA, the normal sli/cf configurations dominate even with resolutions in the range of 1600x1200.

So if you are not going to use above 4xAA with high res, you won't see any benefit to quad sli at all, and may even see a decrease in performance. If, on the other hand, you are going to run some ultra high resolution with 8xAA, you will notice a definite improvement.