Multi-GPU without Wires: Feasible?

CrossFire and SLI Dongle-less/Bridgeless Performance Analysis

by Yaroslav Lyssenko

[ 09/21/2006 | 11:35 PM ]

Since it first introduction in late 90s by 3dfx, multi-GPU technologies always incorporated some sort of connecting bridge or dongle, which provided extra bandwidth or synchronized workloads between graphics cards.

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Recently, both ATI and Nvidia brought to the market multi-GPU solutions which didn’t require any additional interconnections. Hexus.net has carried out an investigation to determine exactly how much performance boost can contemporary multi-GPU setups get while operating with and without bridging devices.

“First things first. Bridgeless SLI... why bother? If the golden fingers are there, use them. On high end cards it clearly makes a difference, and with SLI there’s no faffing about with master cards, so it’s really no big deal. Still, if there’s a problem with the bridge, we’ve shown the performance impact, which is in some cases substantial,” writes Hexus.net.

“For CrossFire, there’s a little more appeal to not having a dongle. It’s not the dongle itself that’s the problem, it’s the expense of a CrossFire Edition master card. Take the X1900 GT, which at the time of writing weighs in at around £120-150, depending on bundle, cooling and what not. A CrossFire edition card to go with that could be £220 or more. So we must ask if the sacrifice made with dongle-less CrossFire is worth the ~£100 saving? It all depends on whether you want the most from your multi-GPU solution, or if all you really need is a boost that’s good value for money. If you’re after the latter, we reckon a pair of X1900 GTs might be the wiser option,” concludes the author.

“Problem is, on our i975X test bed, CrossFire performance and indeed the impact of not having a master card varies so wildly, that the benefit you’ll see really will depend on what games you play. We’d like to think ATI can make performance differences a little more consistent between dongled and dongle-less CrossFire, but we’ll have to wait and see,” adds the author.

• Hexus.net: CrossFire and SLI Dongle-less/Bridgeless Performance Analysis.