XFX Triple SLI - 8800 Ultra's in 3 Way SLI

Introduction

Introduction
 
SLI has been around for a few years and Nvidia have pretty much been the driving force behind multi-GPU solutions since the inception of their SLI solution. Last year they tried to ramp it up a notch with Quad SLI, but this failed to impress enthusiasts, review websites and pretty much the whole industry.
 
Now they've brought in another crazy solution: Triple SLI, or 3 Way SLI.
 
What you need for SLI, according to Nvidia is:
 
 
3-way NVIDIA SLI-Ready GPUs:
NVIDIA GeForce 8800 Ultra
NVIDIA GeForce 8800 GTX

3-way NVIDIA SLI-Ready MCPs:
NVIDIA nForce 780i SLI for INTEL
NVIDIA nForce 680i SLI for INTEL

3-way NVIDIA SLI-Ready Power Supplies:
Please visit the SLI Zone Certified SLI-ready Power Supply website and choose a power supply model from the section For “Three GeForce 8800 Ultra or GeForce 8800 GTX.”

3-way NVIDIA SLI Cases:
Please visit the Please visit the SLI Zone Certified SLI-ready Cases website and choose a cases from the section For “Three GeForce 8800 Ultra or GeForce 8800 GTX.”

3-way NVIDIA SLI Connector:
3-way SLI requires a unique SLI connector in order to operate properly. These connectors may not have been included with your previous purchase of SLI-ready components or PCs. PCs specifically sold as 3-way SLI PCs will have this connector included and preinstalled.
 
SLI...so what is it?
 
SLI stands for Scaleable Link Interface is the marketing name for a way of using two or more graphics processors in parallel. Using both the PCI Express bus and the proprietary SLI connector made by Nvidia, the graphics cards communicate using dedicated scaling logic in each GPU. Load balancing, pixel and display data are passed between each GPU over the PCI-e and SLI connector; basically the two cards share the workload.
 
SLI isn't perfrect, but it is improving as Nvidia revise and re-work their drivers and algorithms to get the best out of SLI. Most situations where SLI is supported see a 1.5-1.9x increase in performance, although unsupported games do not see any at all, some even having a loss in performance.
 
There are three different rendering or balancing modes for Tri SLI, below is an excerp from WikiPedia with the details:
 
 
* Split Frame Rendering (SFR), the first rendering method. This analyzes the rendered image in order to split the workload 50/50 between the two GPUs. To do this, the frame is split horizontally in varying ratios depending on geometry. For example, in a scene where the top half of the frame is mostly empty sky, the dividing line will lower, balancing geometry workload between the two GPUs. This method does not scale geometry or work as well as AFR, however.

* Alternate Frame Rendering (AFR), the second rendering method. Here, each GPU renders entire frames in sequence – one GPU processes even frames, and the second processes odd frames, one after the other. When the slave card finishes work on a frame (or part of a frame) the results are sent via the SLI bridge to the master card, which then outputs the completed frames. Ideally, this would result in the rendering time being cut in half, and thus performance from the video cards would double. In their advertising, NVIDIA claims up to 1.9x the performance of one card with the dual-card setup.

* SLI Antialiasing. This is a standalone rendering mode that offers up to double the antialiasing performance by splitting the antialiasing workload between the two graphics cards, offering superior image quality. One GPU performs an antialiasing pattern which is slightly offset to the usual pattern (for example, slightly up and to the right), and the second GPU uses a pattern offset by an equal amount in the opposite direction (down and to the left). Compositing both the results gives higher image quality than is normally possible. This mode is not intended for higher frame rates, and can actually lower performance, but is instead intended for games which are not GPU-bound, offering a clearer image in place of better performance. When enabled, SLI Antialiasing offers advanced antialiasing options: SLI 8X, SLI 16X, and SLI 32x (8800-series only). A Quad SLI system is capable of up to SLI 64X antialiasing.

Note that Tri SLI generally tends to use 3 GPU AF rendering and this certainly has the biggest performance benefit.
 
Triple SLI
 
Triple SLI works on the same precept as SLI, with 3 cards sharing the load. Unfortunately for the masses who went out and bought the excellent 8800 GT or 8800 GTS, Triple SLI supports only the 8800 GTX or the 8800 Ultra meaning that those without those expensive top-end GPU's will not see the benefit of Tri-SLI.
 
What do we have here then?
 
XFX have kindly sent us three of their top-end  8800 Ultra's to perform the review, along with their 780i SLI motherboard we reviewed previously.
 
SLI boxes
 
XFX 780i SLI
 
Oh, and not forgetting the larger one of the two connectors in this picture:
 
SLI bridge
 
We'll take a brief look at whats inside those rather large boxes, then get into the benchmarks!
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Most Recent Comments

25-02-2008, 04:48:05

Havok
I didn't even expect it to be that good, I am impressed! Crysis still chokes it on V.High too, that game is ruthless.

Maybe with the 9 series soon Ultras/GTX will get cheaper and this might be a viable option before we know it (to those who aren't swimming in money)Quote

25-02-2008, 05:28:16

FarFarAway
Yes it was a pleasent surprise tbh, the 9 series should make it even betterQuote

25-02-2008, 05:57:15

Rastalovich
Great read. The results do look good, and the comment about how the games `feel` is a better qualifier for me.

I`d not even entertain this, even with planning ahead months in advance to afford it. Does look nice tho hehe

Heat is an issue for me; power is crazy talk - but obviously a requirement, which is where the heat is going; drivers and/or a card being tempremental, I can do without, just don`t need it ontop of other pc dodgyness.

All said and done, I`m banking on the top end single card for the generation to come.

Be nice to see single slotted cards or wc solutions of this being tested.

Some fine benches too.Quote

25-02-2008, 08:27:00

Bungral
Unless I came into some serious wedge then its not something i'd consider.. I'm with most here and reckon on a single card top end when it finally arrives.

Quick thing Matt.. Did you give overclocking it a go at all or would it have caused a total meltdown?Quote

25-02-2008, 08:34:05

Phunky
The performance gains does not justify the price at all, i mean seriously why cant they just get standard SLI to just work properly before moving on to tri, quad and so on...

For this cash i would want to see stable FPS, not 40-500fps ranges, you look at any competitive gamer and the key thing for there setup is constant FPS, why else do you think most of them stick to the low 800x600 res?!?Quote
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