I am not kidding, my little Lenovo's internal clock takes a vacation in every 6 months and slows down, refusing to do its work for about a week. This has happened 3 times already, the clock has just came back from its well deserved me time and now it is running good again. I am not talking about a little slow down, but some serious refusal to measure time. Like running 20-30 minutes slow in every hour. If I keep it using, it quickly gets 2-3 hours behind our modern times. So I googled the problem. First I thought it could be the CMOS battery, and I took the laptop apart. Well guess what, it doesn't even have such a battery or I am too stupid because I couldn't find it. (I took inside pictures just in case someone wants to show me where it is) Not to mention it was running slow even when plugged in. The other reason could have been malware. But malwares usually don't go away by themselves, and the clock is back at work after a week, 3 times already. Or maybe Windows is updating some shit in the background? It is certainly a possibility, although I didn't get any notification. The laptop didn't slow down at any other task... So anyway, everything is fine now, and I just have to live with it, the clock will take an R&R in regularly scheduled 6 month periods... If any suggestion why this happening, I have a lollipop for solving the mystery. The internet hasn't been much help... http://www.makeuseof.com/tag/3-reasons-windows-computer-loses-time-date/
You might need a bios update. It might be corrupted. There are a number of programs that are free that will sync your time on a regular basis.
I oddly have this problem with my work computer--no time specific, but I go all army and sync against my phone every 2 weeks or so. There's nothing quite like trying to fire an order off 10 seconds before the bell only to realize it was about 15 seconds ago and your clock is just slow. It's an off-the-shelf feature with newer version of Windows to update from the internet. I'm thinking my personal issue with it has to do with being connected through a server.
1. If the BIOS is corrupted, why does the correct time come back after a week? 2. Why would I use a band aid fix of an app if I could actually fix it with an update or correct driver or whatever? My best guess is that maybe Windows is updating in the background and that somehow slows the clock down. W 10 got downloaded for me without my permission before, so it is not completely out of the question.
There are ways to turn off all that automatic update/download crap in Windows 10 if you do some searching. If you feel like this is your best guess as to what the problem is, you might want to look into that.
Apparently W7 syncs once per week but that can be made more often. (Task Scheduler>Library>Microsoft>Windows>Time Synchronization>Synchronize>Triggers>etc.) In the main time: http://www.worldtimeserver.com/atomic-clock/
Last night Windows updated and by the morning the clock was 80 minutes behind. Now it is running 20 minutes slow per hour... I guess I am going to do what I described in post #8, synchronize it in every 10 minutes.