Microsoft improved Windows loading time by introducing a new operating mode, called sleep mode. What appears to be a shutdown button on the Start menu is in fact a sleep button (it is dark orange, see Figure 15), which does not turn off your PC, but puts it under sleep mode. When you turn on your PC again it will take just a few seconds for it to load Windows. The side effect is that your PC will be exactly like you left it – the same programs and documents will be open. We made a test with our PC and it took less than 12 seconds to restore our desktop. In fact it could be faster than that, but we were using a CRT monitor, which delays a couple of seconds to warm up and start showing any image.

Figure 15: Sleep button.

Options to save energy will also put your computer to sleep if you don’t use it for a while. The default settings for our Windows Vista Ultimate were to put our PC to sleep after one hour without using it. You can change this configuration at Control Panel, Power Options icon.

But pay attention because if you push the on/off switch located on your PC case to turn off your computer, it will really turn it off, not putting your PC into sleep state.

Here we want to explain in details how this sleep mode works.

If you are a laptop user you may be already familiar with the hibernate state. Under this state all the contents of the RAM memory is stored in a file on the hard disk drive and then the system is turned off. When you turn on your laptop again, the contents of the RAM memory is restored from the hard disk drive file and you have your computer just like you left it before putting it into hibernate state.

Sleep mode, on the other hand, turns off all components of your computer but the RAM memory. The memory is still fed by the power supply, even though the power supply appears to be turned off. This is possible because one of the power supply outputs, called standby power (or +5VSB) is always turned on, even if your power supply is apparently turned off.

So when in sleep mode your computer appears to be turned off but its power supply is still feeding your RAM memory. When you press the on/off switch on your computer case, the power supply is turned back on and all other components are turned on again. You enter Windows directly because Windows, your programs and your documents were already in the RAM memory.

There is just one problem with sleep state. If you really turn your computer off – i.e., remove your power supply from the power grid – the contents of your RAM memory will be lost and the next time you turn on your computer you will have to load the operating system all over again. So if you want to keep you PC in sleep state, do not remove the power supply cord from the wall, do not turn off the power supply main on/off switch (some power supplies have this switch, which is located on the rear side of the computer) and do not turn off your UPS, voltage regulator or surge suppressor if you are using one.

Also, since you always have the chance of losing the contents of your RAM memory as someone may turn off your computer without knowing it, only enter sleep state after saving all files you were working on.