Problems with sleep state with a high OC.

When I go over a certain frequency the system will not fully enter sleep state. It powers down all but the fans and lights. When this happens I am unable to wake the system by keyboard or mouse and need to reset the system. My system specs are in my SIg and profile.

Before you say the OC is unstable at the higher frequency, It passes all tests it is put through: IBT @ 40 runs on max memory, Prime 95 for 8 hours, Memtest86+ for 12 runs or more.

This is not the only system I have run into this issue with. My old system that I have for my son to game on does the same thing. Both run Windows 7 Home Premium x64.

STABLE and sleeps/ STABLE and doesn't sleep proper
Cpu: 965
Name: Bgunner
Stepping: C3
Frequency: 4096 / 4011 and over
ref*multi: 240.8*17 / 241.8*17 and over
CPU voltage: 1.42
CPU-NB: 1.28750
nb frequency: 2648.8
NB volts: AUTO
RAM: 8GB 1600Mhz DDR3 9-9-9-24-1T @ 1.50V
Motherboard: Asus Sabertooth 990FX r2.0
Cooling: Air cooling/Hyper 212 EVO
OS: 7 64-bit
GFLOPS: 54 (Only for LinX)

Upping the voltage does not help. So at this point I am left to asking Why are the systems having such issues with S-states and sleeping? Is there a fix for this besides just not letting the system sleep?