Yea, sorry, I got caught up in researching something on my car and then went to bed. I 'think' I found another guide you to at least view. It's best to read it over first, to get at least a basic idea of what they are doing, then try to change things.
Haz has mentioned all the basic solutions to the problems you're having. Such as sleep being related to C states. Usually under a section in the bios related to CPU advanced power settings. Most boards show C1E, C3, C6, and 'Package C State Support'. All with enable/disable as options.
As for your RAM, the package or the RAM sticks themselves should have the voltage they use and the some numbers generally listed like X/X/X/X (commonly 9/9/9/24). Or you can look up the specs online and see them listed the same way. On the motherboard this usually shows up in DRAM Configuration. You definitely want the voltage to be correct, instead of just using auto, since this is overclocked RAM. Voltage and the 4 other settings will probably determine whether or not you reach the 2400mhz.
Thread below is for your board, but I don't have an ASUS account to download the images or PDF where someone made a guide for it:
http://rog.asus.com/forum/showthread.php?9247-BIOS-Screensots-of-Stable-4.6-Overclock-P9X79-Pro
The guide for ASRock boards, which I have, does a decent job of breaking down what some of the settings mean, which may be of help. I'd give it a read through.
http://www.overclock.net/t/1198504/...-guide-sandy-bridge-ivy-bridge-asrock-edition
For starters, I would default all your changes in BIOS, make sure it runs, then make changes to your RAM voltage and DRAM settings to the specifications that your RAM states. If you can't get 2400 with those all correct, just go down to the 1866, but try to get all the settings spot on first.