Chris Samuel said,

Out of interest, why build such an old kernel for this?

If you're after the latest ACPI code you'd want to try a 3.10 kernel (or from Linus's tree if you want to test what will be 3.11).

Several reasons, when doing any work in a new area, ie research work, in this case 64bit, one should __ALWAYS__ work from a known starting point. In this case 3.7.9 was the last kernel I had compiled that I knew worked. Second point is this particular machines main purpose is a development platform for a real time 3D terrain simulation and uses the NVidia closed source driver. One needs to tread I little carefully on new versions of this (same with the AMD driver). I had trouble getting the version I am using working with a later kernel (3.8 series). I am not really interested in ACPI execpt it gives trouble on this particular machine, given the machines primary use low power consumption is a non issue. Sitting right next to it is another machine of good deal lower specs that is used for normal every day work. This message is being writen on it. It would probably be a good idea to try a latter kernel from the 3.10 series (or what ever) to see if the ACPI issue has been sorted, the MB chips set (the X79) being fairly new. I will probably do this in time. Using Linux for 20 years, kernel 0.96d being the first one, Lindsay