I made that mistake up until a month ago or so. Two eVGA 6600GT's on a Athlon64 3500+ OC'd ASUS A8N-SLI Deluxe 1Gb XMS3500C2PT with SATA Raid0. I saw a definite improvement as soon as I pulled the second GPU with increased FPS and less stutters. I've traded in the pair for an eVGA 6800GT and I couldn't be happier.My theory is, on one PCIx card you are running full 16 pipelines throught the first GPU. When you insert the second card, enable SLI in the driver or not, you split the pipelines in half, 8 for each PCIx slot. This game will not utilize the second GPU/PCIx slot to any great extent and you lose half your GPU bandwidth through the first PCIx slot where most of the game is being processed.If your rig is for FS, spend the money that you would have spent on two GPU's and get a better single card. You'll be happier. Hope this helps....Al

I have yet to see any improvement of SLI. Right now, SLI is nothing more than hype, because developers have yet to develop for the new technology. If they're not, then SLI is nothing more than an interesting idea. The hardware manufactures want to make us believe that the latest inventions are a must-have, when they're in fact not (or not yet).

I don't think SLI is a bad idea, it allows for multiple monitor setups or redicting all the GPU's power towards a single display for gaming performance. Flexibility is always a very positive trait. The big problem here is FS9. Its old, antiquated graphics engine and outdated DirectX hooks will never take advantage of today's hardware. SLI does improve games being released today (well, depending on the game and driver version) but eventually I think it will mature. The only part I will watch into the future, is Nvidia's continued support for Driver profiles and tweaks. This is going to create a lot of maintenance overhead and it'll be interesting to see how long they continue to do it. BTW, I could be mistaken, but I don't think game developers have to code anything specific to SLI. As long as they are using the proper driver sub-routines regardless of the driver's SLI setting. One good aspect of the game profiles being included with the driver is we've been getting more driver releases lately....Al

SLI when used with games that really take advantage of it is a huge improvement over a single card. FS9 is pretty old (in computer software terms) and is mostly CPU limited and not written with SLI in mind. FS10 looks like it will be a little more shader-intensive but I doubit SLI would help much unless you run at 1600x1200 with 6x AA.I still think SLI/Crossfire will always be a super-high end feature and never a must-have. Not everyone can or wants to buy two $500 videocards. It's not just a matter of money either, the system will run hotter, make more noise and draw more electricity.

I agree, Jimmi.And benchmarks by Tom's Hardware Guide (http://www.tomshardware.com/) reveals the fact that a single nVIDIA GF7800 GTX will give you more fps than two SLI GF6800 Ultra cards. And the single 7800 GTX comes a lot cheaper.Ulf B