Windows Stand By Maintains a Fast State of Readiness When you hear the term “stand by” you think of a resource that is ready to go once called. The concept is similar in Windows. Your computer returns to a state of readiness when you press a key or the power button. The time it takes your PC to resume or shut down is seconds. Your machine recovers quickly as your data is stored in RAM. The slower part is waking up the peripherals. Although your machine is in “stand by” the power has been cut to items such as your hard drive and monitor. You’re running your machine in a very low power mode, but it is still on. This mode can be useful if you’re on a notebook and need to conserve your battery while you step away. If you have a notebook, you wouldn’t want to keep your computer in this state for more than several hours. The first issue is that even though you’re in a low power consumption state, you’re still using power. The bigger reason is once your power goes, so does your data. The big drawback to Stand By is you run the risk of losing whatever data you were working on if the power goes out. As a precaution, you might want to save the data before putting your computer in this mode or use Hibernate.
  Windows Hibernate Takes a Longer Term Approach An option with a longer perspective is hibernate. Like Stand By, you can recover your place. The big difference is that your PC has shut down and is not pulling power. Another difference is that your data is saved to your hard disk and not RAM. This makes it a safer, but slower option for shut down and resume. Hibernate will save your desktop and open files to a special Windows file called hiberfil.sys. This large file usually resides in your root folder (c:\hiberfil.sys). The file size closely matches how much RAM your PC has installed. If you have 2 gigs of RAM on your notebook, you’re going to have to give up 2 gigs of hard disk space. Note: You can delete the hiberfil.sys file only if you disable hibernate. When you press your power button, Windows will start and open the files you were using. The process is not instantaneous as with Stand By, but gets you to the same place. You may find this option is faster than rebooting, as Windows doesn’t have to do things such as detecting your hardware