SLI Scaling

Value and Conclusion

Good things indeed come in small packages. While NVIDIA is modest about expectations from the single GeForce GTS 450, recommending it mainly to users of 1680x1050 resolution, the SLI is quite a revelation. The GTS 450 SLI duo scales best at HD and beyond-HD resolutions (1920x1200 and 2560x1600), offering well over 80% performance boost overall. This allows you to quickly transform your setup for full-HD gaming, with no reduction in image quality, and maintaining 4x AA settings. The best scaling was noticed with the latest DirectX11 and DirectX10 games. This shows that SLI is a better option if you're looking to step up your display resolution, than for simply increasing frame-rates at the same resolution.
In terms of performance relative to high-end single-GPU graphics cards, the GTS 450 SLI stands tall for its price. It outperforms the ATI Radeon HD 5850 (priced as low as $259.99 on Newegg.com), at the same price. It gets close to the GeForce GTX 470 (cheapest goes for $279.99) while being still being cheaper. Like I said earlier, by the time you're going to buy your second card, the second card will be cheaper, so don't take $260 really at face value. One can't use the same argument for say Radeon HD 5870 CrossFire or GeForce GTX 480 SLI, because back when the two solutions launched, there wasn't a single-card alternative for either of those, at their respective price points.
The GeForce GTS 450 has shown some impressive power consumption figures in its single-card form. A typically-configured gaming PC with GTS 450 SLI should run just fine with a decent-quality 500W power supply. The coolers on some of the cards are extremely quiet, and so running two of them won't really qualify as noisy. Expect a bit more noise though because one card will run hotter because its fan will be sitting right behind the PCB of the second card (on motherboards with single slot spacing).

Overall, the GeForce GTS 450 SLI is impressive. It gives you exactly the flexibility you'd want when building a cost-effective gaming PC, and later giving it a great graphics performance boost with a second card. The GTS 450 SLI can handle any of the latest games at HD resolutions. Go for it if you want to buy graphics hardware in two installments of $130-$150 each. If you have $300 to blow upfront, buy a single graphics card, like the GeForce GTX 470 or the Radeon HD 5850 and leave yourself room to install a second graphics card whenever you can afford it or feel you need the performance.