ASUS P8P67 Series Motherboards

Same reason you would buy an i7-2600K over an i5-2500K is why you would choose triple-channel over dual-channel.

For gaming, i5-2500K is 100% sufficient, without any problems. Power users though (extreme overclockers, benchmark addicts and people focused on high-performance computing like in the video editing industry would gain from the more powerful i7-2600K with something like 12GB of DDR3 in triple channel configuration. The average user/gamer wouldn't even notice a difference in performance between dual and triple channel, so there's no need to spend extreme cash on the motherboard/RAM combo at all.

Stick with dual channel, it's fine as it is  

Thanks Leaps and Toxxyc!

You both raise another concern: I am planning on using this build for 3d modeling on AutoDesk Maya and AutoCad as well as using it for Adobe CS5. I've been waiting for the updated Asus P8P67 (B3) motherboard and the purchase of an Intel i7-2600k (Sandybridge) processor. Is this a mistake? Should I be going for the slightly older Asus P6X58D Premium motherboard and an i7 Bloomfield processor instead?

Best answer selected by jiroband.