My Bad you are correct!!!
G-series is SANDY BRIDGE, I misread the title.
On support of Ivybridge with current 6-series MBs (P/H6x and Z68).
Concur that the x6x series MAY support IV with a Bios update. Possible problems and at mercy of MB manuf.
Quote:
The opposite should also be true, but VR-Zone states that older LGA 1155 6-series motherboards could have problems when paired with the upcoming Sandy Bridge processors.
These could be caused by the fact that Intel won't release its cross compatibility guidelines until sometime later this quarter, although the Santa Clara based company is doing its best to speed things up and solve this issue.
End Quote
Ref:
http://news.softpedia.com/news/Intel-LGA-1155-Sandy-Bridge-Motherboards-Confirmed-to-Be-Compatible-with-Ivy-Bridge-CPUs-185047.shtml
.. While the current x6x series may support the IV, they will not support some of the feaures that will be included with the x77 series such as sound and native USB3 support.
Also See: http://www.guru3d.com/news/intel-7series-ivy-bridge-motherboard-chipsets-to-arrive-in-q2-2012/
My thoughts are that if a individual is going to spend $500+ bucks on a CPU they will also go with the x77 MB.