SLI continues to be a great technology. Crossfire is as well. Both have come a long way since their introductions. It's great to see that the GTX 470 series scales well and we've got our fingers crossed that the same scaling ability is seen on the higher end GTX 480 when we have a look at it.
When you start talking multi GPU setups, though, the decision is going to be tough; do you spend your money on the GTX 470 in an SLI configuration or do you have a look at a HD 5970? - Both offer similar pricing. On a whole, though, the GTX 470 SLI setup is faster and this can be seen in our TPR graph.
Looking at the pros, the big thing is that a GTX 470 SLI setup will outperform a reference HD 5970 while costing similar money. The good news is if you're thinking about going surround gaming as well, you can buy two GTX 470s for a similar price of the HD 5970 and know that performance should be similar. Mind you, we haven't had a chance to look at surround gaming so we're not sure how the software solution that NVIDIA have opted for is going to go.
Now, let's cover the cons. Power draw on the setup is higher than anything else we've tested in both idle and load. Saying that; a good 750 Watt+ power supply isn't going to be an issue and if you're looking at a setup like this you should have a good power supply anyway or be looking at something decent.
The good news is that noise levels aren't really any worse than a single reference GTX 470, but heat on the top card is going to be worse. Our graphs show this and you have to remember that Palit and Galaxy have opted for new coolers. Throw in reference coolers and the cards are going to run even warmer.
While some might say that the heat isn't a big issue, my office is quite a large room. I actually use the house's theater room as my office, so that should give you a bit of an idea. With my testbed up and running the room was clearly warmer. Considering we're heading into winter over here in Australia the comment of these cards being a heater in the winter is very true and this is dealing with non reference coolers. The heat of the cards is something you've really got to put into consideration. Keep your computer in your room or just a small room in general and there's a good chance you're going to feel the warmth of these cards; a situation that would become even worse in the summer.
It's going to be a tough decision if you're in the $700 region and looking at a video card. At the end of the day the GTX 470 SLI setup is not only a little faster than a reference HD 5970, but also a little cheaper. You can't ignore the heat issue which is much more noticeable than both the noise and power ones. Now you just need to decide what you want to do and at the end of the day you could always just get GTX 480 SLI and be done with it.