I have a PC with Windows 7 64x. I created a file (text file, for example). I write some text into the file, and after that I save it.
If a power failure occurs and the computer restarts, the file exists, but it is empty. It has lost all information that I've written to it.
I have tried to disable Windows 7's hard disk write cache, checked the BIOS and I couldn't find anything.
I have done this test in several machines with Windows 7 with the same results. You can try it for yourself: As I said, just create a .txt file on the Desktop, include some text and remove the power from the computer.