Hibernate preference panel will allow you to switch between different sleep modes on your Mac.
- Hibernate & Sleep
Hibernation should work on a PPC Mac running at 1GHz or higher. The NVRam patch is required for some machines. This means that some values are stored in the computer's no-volatile RAM to indicate it is hibernate capable. These values are checked when the OS boots up. To enable NV-Ram Patching, the software currently checks for machines greater than 1 GHz. Some machines won't sleep at all and some won't turn on hibernation. If hibernation goes wrong, you can reset it by pressing CMD-ALT -P-R during booting.
Use this software at your own risk. Apple may have a reason to allow hibernation on older machines.