Computer clock time changes when booting from a DVD?

Question

Okay so currently I'm using Windows 7 Pro 64 bit.  Yes I know it is out of support.  Here's my problem.  If I boot with a DVD with Linux Mint 19.3, or Ubuntu 20.04 LTS, and run a live session using the DVD, when I boot back into Windows 7, the time will have changed.  Now if I change the time back to what it's supposed to be, and then shutdown and boot back into Windows 7, the time will have kept.

Even if I shutdown for two whole days, and then turn the PC on and boot into Windows 7, the time will have kept.  BUT.... if I boot into a Linux DVD, then boot back into Windows 7, the time will be different.  I know it's not a CMOS battery issue because I shut my PC down every night before going to bed, and when I boot up, the time is what it should be.

Any reason why this might be happening?

? · Accepted Answer

Anonymous is right -- Linux is assuming your computer's CMOS clock is set to UTC, while Windows assumes it's set to the local time for whatever time zone Windows is using. The "time" is right, but they're just applying different offsets. And if the time difference is too much, then the automatic time syncs that take place might not happen unless you tell it to.

Anonymous · Answer

You're certainly running non-standard and neglected to mention hardware at all.
We know clock adjustments in today's PCs come from the internet. We know when you change from Windows to Linux you run a different driver set and essentially resetting your system. 
There is probably an article on the internet somewhere, but it's outside my typical hardware expertise. 
Clock and cmos battery are not used the same way as for windows XP.

Anonymous · Answer

One of the OS's is assuming your hardware clock is set to UTC and the other assumes it is set to local time.

Computer clock time changes when booting from a DVD?

Trending Questions