Quad SLI adds double the considerations in a physical sense, and you must certainly make sure the rest of your PC is up to the task, in many ways. However, if it's something that appeals, then the tools are at your disposable for enjoyable high-res gaming in a number of supported games titles. It begs to be paired with a high resolution display (we tested on 24 and 30 inch widescreen LCD monitors, which are the definite target display to connect), and in our opinion the ideal partner is something like a Dell 2405 or 2407, 24" widescreen display.
The pixel count lets you run 1920x1200 at good framerates, and in games where Quad SLI simply eats that up, 8x SLI anti-aliasing becomes a usable IQ enhancement that you might never have enjoyed with 2-GPU SLI, the same hardware as a given. Stability seems decent, NVIDIA apparently fixing a lot of the warranted criticism with 7900-based Quad SLI first time around, making it much more appealing from the end-user's standpoint.
Therefore if you're prepared to put up with the compatibility with games and hardware, you have the rest of a great PC to host the boards and you have a suitable display for it to draw only, DIY Quad SLI has certain appeal. It's expensive, but then that's rarely stopped those who enjoy a powerful beast of a PC.
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