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.