So is it worth your money?
Evaluating SLI's worth at the time of writing, with the three card pairs available, is dependant on whether you want to jump to SLI straight away, as soon as you can, or whether you wish to use it as an upgrade path.I want it now and I can afford it!
OK, you're easy to deal with. Get 6800 GTs in SLI. Next question.In all seriousness, it's quite easy to justify that at the time of SLI's launch. 6600 GT's don't buy you anything over a single 6800 GT for the most part. Add to the fact that a 6800 GT on PCI Express is barely £20 more expensive than two 6600 GTs, you get the same performance for the same money with that single, more capable board, and you still leave a slot free on your SLI mainboard. Performance is close enough to 6800 Ultras in SLI for you to not bother considering them either, especially not for their price premium. So if you want SLI and two cards, make sure that's enough for 6800 GTs or higher.
I want a single SLI-capable card now, and one later!
Your case is much harder to evaluate. There's a fixed cost of at least £140 for the mainboard to consider, before you even consider the cards you want to use. And that assumes you already have an Athlon 64 Socket 939 processor and suitable memory, and the rest of the PC system too, to build your SLI system around. With Tumwater an unattractive SLI platform for the gamer or SLI-adopter that doesn't want to spend a fortune, that leaves you with Socket 939 Athlon 64 as your only choice.If you're a newcomer to Socket 939 entirely and you're going to be moving to that at the same time, I'd definitely urge you to factor in the cost of a single 6800 GT to the equation. It's an extra £120 cost over a single 6600 GT, but it's well worth the investment. I'd also urge you to make the Athlon 64 3500+ your slowest processor choice (if you don't have a CPU already), to save yourself from being overly CPU limited when you add the second card. If you're going to consider 6600 GT for SLI, you can drop that down to the entry-level 3000+ processor, but even then I'd advise against it in the long run, unless you're going to upgrade your CPU again at a later date.
And it's these factors that make it inherently difficult to measure SLI as an upgrade path. You're CPU limited even on FX-55 sometimes, and that draws the CPU into the equation, along with the SLI cards and mainboard.
Rolling in the cost of the base SLI platform, it seems logical to me that most people considering SLI as an upgrade route are going to wish to use 6800 GTs. The cost of the mainboard on its own seems too high to be attractive to those wanting to use 6600 GTs.
There's a fixed cost of at least £300 if you want to take this route (at least the mainboard and a 6600 GT). If you're contemplating spending that at the very least, seriously contemplate saving up the next £150 to make sure your starting card is a 6800 GT.
I want SLI, but I want to keep my current non-SLI-able PCI Express graphics card for a while too
Well, that's kind of hard since SLI demands PCI Express and PCI Express for AMD is in its infancy. I'll assume you're selling an Intel system of some sort to fund the initial leap to the platform and you're taking a cheap, non-SLI-able PCI Express card with you.Your fixed cost is at least £140 or so, for the mainboard, at the time of writing. Again, I'd urge you to consider a decent processor for that mainboard and aim for at least the 6800 GT down the line, when you come to pick up your first SLI card. Since you're not even picking up a single card just now, that'll become more financially viable in the future. Make sure you either plan to buy quite soon, since NVIDIA might very well release more SLI SKUs, or wait until March time to see how the GPU land lies. This upgrade path should be very uncommon however.
Availability
NVIDIA's SLI-able graphics SKUs are available in decent numbers to buy right now, with the exception of the 6800 Ultra. Prices start at around £150 for a 6600 GT on PCI Express and £310 for a 6800 GT, from a number of large online retailers.Mainboard wise, we're still waiting for hardware to hit the market, either at SIs or at general retail. Initial indications were that ASUS and MSI would be the only two mainboard vendors to ship nForce4 SLI products this year, however Anandtech have indicated that Gigabyte are just about ready to ship too. Pricing is going to be on the far side of £140 initially, with a guesstimate putting ASUS's most deluxe model nearer £200. So while availability might well be quite high before 2005 rolls round, so will first-round prices.
Summary
I maintain that 6800 GT in SLI is the most attractive SLI solution whether you're buying it all now, or one now and one later. Given that PCI Express for AMD has just shown up, it's safe to say that people contemplating SLI on that platform will be buying brand new graphics soon for it, since they're coming from AGP and SLI requires SKUs that are only just making it to market in large numbers.And if you're doing so, 6800 GT offers either great base performance in single card mode, or outstanding performance in most titles in SLI mode. 6600 GT, had it have been a fair bit faster than 6800 GT or Ultra, would have made a better case for itself. 6800 Ultra remains the card of choice for the deep of pocket only, single card or not!
In some respects, considering this first round of SLI hardware only makes sense if you're willing to jump on it right now. And if you are, I'd bet you're well off enough to get 6800s.
SLI's obvious competing technology is ATI's AMR and VIA's DualGFX (although it remains to be see just what VIA are doing to do with it in terms of 3D acceleration using two cards), both of which won't appear en masse until 2005. For now, if SLI is what you want, my advice is to aim for 6800 GT at the minimum.
