text: each time i log on my computer, i have to reset my clock..what is wrong? i didn't use  to have to do that.   the battery on your motherboard (cmos battery) is dead. you can buy them at many stores. they are size cr2032. they are usually easy to find on the motherboard, flat and round silver thing. sometimes though they are hidden behind the video card. you may need to use a small flathead screwdriver to help in getting it out.