RC6 power-savings support has been attempted before for the Ironlake graphics found on Clarkdale/Arrandale CPUs, but ultimately it's been reverted due to issues. RC6 can lower system power use as a lower power-state introduced on Intel processors a few years back. RC6 has been turned on for newer hardware and there were some common RC6 issues many kernel releases ago, but now it seems to be in good shape now for Sandy Bridge and newer.
Appearing today on the Intel graphics mailing list are a set of nine Ironlake (ILK) patches that should make it okay to try re-enabling RC6 power-savings for the older Intel hardware.
Let's hope this latest time is the charm for this power-savings support on Linux for Ironlake hardware owners. With the timing of this patch-set though, they're unlikely to be merged until the Linux 3.13 kernel as the Linux 3.12 kernel merge window is only open for one more week. The good news is this could maximize testing exposure but for those end-users relying upon distribution-shipped kernels, then it will not be until 2014 when your Ironlake hardware can maximize its power efficiency under Linux.