XFX 9800GX2 Quad SLI

How it Works & Requirements

Quad SLI - How it works
Briefly, SLI (Scalable Link Interface) works by combining 2 graphics cards together to render images quicker or indeed with higher settings such as AA/AF. It does this by using one of two methods:
Split Frame Rendering - A process by which each card 'draws' a half of each frame so that every frame you see on the screen is actually processed by both GPU's.
Alternate Frame Rendering - Does exactly what it says on the tin. Each GPU processes a single frame allowing the frames to then be rendered ahead of time preventing any bottleneck of processes waiting to be rendered. This process is called interleaving. One GPU will process one frame while another GPU will process the next, taking it in turns to render the frames.
Quad SLI however first encountered problems with the old 7950GX2 because DirectX 9 was incompatible with 4-way AFR so a mixture of both SFR and AFR was used. SFR is much less efficient than AFR in the latest games due to the amount of complex textures, lighting, ray tracing which is now incorporated in todays modern games era. Due to this and DX9 incompatabilities, the 7950GX2 simply didn't work too well. With DirectX10 now upon us, 4-Way AFR is now not only feasable but with the optimised drivers from Nvidia becomes a very viable solution to those wanting to game at high resolutions with all the trimmings.
4-way AFR
As we will be testing a top of the range setup it should come as no surprise that you will need the best equipment if you are going to take maximum advantage out of the QUAD SLI experience. Here is what I would recommend:
  • Monitor. I really wouldn't bother with Quad SLI if you intend on running at resolutions below 1280x1200. The reason being is that at that resolution the benifits will be so small that the advantage of running a Quad SLI system is lost. SLI in the past has recieved mixed reports with some swearing by it and others giving scathing reports. I believe a lot depends on what resolution SLI was run at.
  • Motherboard. You will need an NVidia based SLI capable motherboard along with 2x 16 speed PCIe slots. Although Quad SLI is reported to work on older Nforce 4 chipsets I would recommend either NForce 680,780,790 boards as the old NForce4 mainboards will cripple your choice of CPU which in turn will hinder the performance of Quad SLI.
  • Memory. The more the better. The faster the better. Simply put this is one area where you will see a benefit of getting higher capacity modules.
  • PSU. Anything less than a household nuclear reactor won't be sufficient. You remember Chernoybl - they tried running Quad SLI on a cheap PSU and look what happened. Ok, so I have exaggerated - As each GPU pulls apx 198W of power, a good mainboard, overclocked quad core, high speed ram and your other peripherals can easily take the power consumption of a Quad SLI rig into the 800w mark. I would therefore recommend a PSU that weighs in at least that wattage - and make damn sure its a quality one with powerfull rails otherwise you can kiss goodbye to it (and possibly your Quad SLI setup) pretty soon. You will also need to ensure that the PSU has both 2x8 pin and 2x6pin PCIe connectors.
  • Case/Cooling. Something that is often forgotten when considerring those nice lush new graphics cards. First of let me tell you that if you can fit an 8800GTX in your case the the GX2 will also fit. As for cooling then I'm sure you have seen the video making the rounds about some nutter frying an egg on one of these cards so it goes without saying the GX2 is a hot sucker. Add another card and you have the means to not just fry an egg but start your own roadside cafe. Make certain your case has good ventillation with a nice influx of cool air otherwise things will overheat pretty rapidly.
  • Money. Yup these cards are expensive. Buy two of them and you won't be getting a Christmas card from your bank manager, your wife may file for divorce and you'll be living in poverty for a while but hey who cares - you will have the fastest gaming rig money can buy...right?
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Most Recent Comments

22-06-2008, 10:49:22

With matured drivers we take a look at where your money should go with regards to a Quad GPU setup. XFX 9800GX2's or ATI 3870X2's.


22-06-2008, 11:31:57

nice review mate,and very impressive results.However I can safely say that there is no way I could justify spending that amount on gfx cards,but would love to try it outQuote

22-06-2008, 11:49:45

Yeah it's alot of money to fork out on GPU's and I don't think I could justify paying that much but before doing the review I was more than content with my quadfire setup...now I have my doubts after playing with the Quad SLI setup.Quote

22-06-2008, 12:01:34

Very nice mate very in depth

whens the 4870 crossfire and 280gtx reviews?Quote

22-06-2008, 12:07:58

nice review... shows everything i wanted to see here.. too bad i cant afford the gx2's. 48*0's should be good though. wouldnt mind seeing a review comparing these to the G260/280


22-06-2008, 12:09:30

looks good

but yea, a 4870 in crossfire also would have added nicely to the comparison

but i'm guessing you can only do so much Quote

22-06-2008, 12:10:03

Nice, you can really see quad sli make its own at 2560x1600Quote

22-06-2008, 14:42:05

Cheers. Yeah it would be nice to test the latest and greatest , especially in SLI/CrossfireX - watch this space.

As a side note would you all prefer the res to be turned down a little as I know not everyone has 24-30" screens (although you should!).Quote

22-06-2008, 16:33:41

Nice review again Rich I think the price is far too high even for the half decent high level performance seen here to be honest

Plus those babies get majorly hot and majorly loud Quote

23-06-2008, 05:45:22

One thing that bothers me is how the gx2 takes 2 slots and the single pcb cards take 2 slots.Quote

23-06-2008, 10:22:20

Basically both GPU's are still cooled efficiently as the GX2 has one large cooler attached to both cores(one either side of the cooler) rather than each core having a separate cooler. The downside to this is that the heatsink needs alot of air to be passed through it which in the GX2's case means more noise.Quote

23-06-2008, 11:24:19

What screen you on webbo? a 30" im guessing... Nice review I can see its not really worth it for me on 24, unless I add loads of AA Quote

23-06-2008, 13:38:49

30" although as the results show a 24" would also be affected though not as much as the res is scaled down.Quote

23-06-2008, 13:39:45

:O lucky buggerQuote

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