Legit Reviews posted a review on Hybrid CrossFire
AMD Introduces Hybrid CrossFire - 780G and Radeon HD 2400
When it comes to performance the Radeon HD 3450 isn't going to dominate any games, but it does score a respectable ~1650 points in 3DMark 2006 on the test system powered by a 2.2GHz AMD Phenom processor. If you enable Hybrid CrossFire the score in 3DMark 2006 jumps up to ~2660 points, which is a boost of over 60%. We didn't get a chance to see the ATI Radeon HD 3470 graphics card in action, but AMD said it should score over 3000 points when run in Hybrid CrossFire on 3DMark 2006. AMD let us try out Call of Duty 4 at 1024x768 with decent quality settings on the system pictured here and we were seeing 20-50 frames per second Hybrid CrossFire enabled...
AMD Introduces Hybrid CrossFire - 780G and Radeon HD 2400