Sleep works but wake doesn't, and after wake the BIOS is reset.
Is there a fix?
It's your appleRTC that causes the problem. In my instalation I guess [url="http://www.insanelymac.com/forum/topic/279450-why-insanelymac-does-not-support-tonymacx86/"]#####[/url] installed that automatically with Chimera. Here's my AppleRTC file below, this should solve your problem. Also I highly recommend to use F7 bios version.
I have built a hackintosh with the GA-Z68X-UD5-B3, Asus HD6870 EAH6870DC2DI2S1GD5 and OCX Vertex 3 SSD and 16GB Corsair Venergance 1866. I have installed vanilla 10.7.2 from USB drive (prepared with Kakewalk). After the first boot I used [url="http://www.insanelymac.com/forum/topic/279450-why-insanelymac-does-not-support-tonymacx86/"]#####[/url] to install Chimera, the DSDT.aml from tonymac, iMac 12.2 system identifier. That's it.
Only modification to BIOS (version F7) was HPET set to 64 mode and SATA mode to AHCI. I also disabled onboard audio because I don't use it.
The system works just like a mac, power management works great, even on the Ati 6870 int works just like an Apple card, without any intervention, sleep works (but you have to keep clicking the mouse until you see the desktop). I stressed the system in some benchmarks about 3 hours and it's rock solid.
So that Asus video card I used seems a better solution than the Nvidia 580 because it works vanilla OOB.