Safe-mode is when you have a problem and you are trying to diagnose what the problem might be. Let’s say you have some malware or a virus, the safest way to remove these problems would be to go into safe-mode. If you are using Windows XP, Vista or Windows 7, the quickest way is to hold down the F-8 key or hitting the F-8 key repeatedly.
For Windows 8, there are some steps that you must take. First off, pull up the Charm Bar, go to Settings, “change PC Settings, Move down to Update and Recovery,this will take you to another page, Move down to where you see the word” Recovery”, Under Advanced Start-up, click restart.
After restarting the computer, you will have a few options: Choose Troubleshoot> Advanced Options> Start up Settings> Restart the computer, and this will take you to Startup Settings, press the number 5 on the keyboard, which is Safemode with Networking. Using this will enable you to update any anti-Malware program, or anti-Virus. Use the administrator account in Safe Mode.
below is link of what devices are working during safemode
This is a break-down of all safe modes:
booting into Windows Vista
booting into Windows 7
link for using diagnostic tools in safe mode
Putting GOD First
Be safe and Aware