most mornings my computer has lost 8hours on the clock ..anybody know why ..thanks?

Yes it probably the bios / cmos battery going duff as that is what powers the memory that retains such things as the time and date when the computer is switched off, it is usually a CR 2032 and costs about £2, replace it with the side with the writing on visible, and switch the pc off first and try not to touch any other motherboard components with your hands whilst you are changing it or the static electricity in you may cause damage to the motherboard components;

http://www.computerhope.com/issues/ch000239.htm

You can actually set the clock to be updated over the internet, which might not be of much help to you if it only does it once a week, but anyway, here are Microsoft`s instructions about how to do that ( look for sync with internet time server ) and everything about the clock and time zones as well;

http://windows.microsoft.com/en-us/windows/set-clo...

Or, if you have Windows 7 (might work with earlier versions as well) left click on the time and date in the system tray bottom right, left click on change settings, left click on "internet time" at the top, make sure that it is set to get the time from the internet server, or change it to that, click on apply ,OK, then exit the screen.

You always give such detailed answers on here in other sections that I thought you were worthy of more than a 1 or 2 line answer, even if they were right.

Edit, just thought, if it losing exactly 8 hours it might have reverted to being a West coast American one, so it is worth checking the "time zone" settings which are also in the Microsoft link.

Regards, Bob.

CMOS battery

Hi so it needs a new one it is a button cell on the motherboard.

most shops that sell small batteries sell these cells. one is all that is required.

CMOS battery is failing.