Hardware clocks and dual boot

Tue, 30 May 2023 10:17:56 +0100

So completely random (as always I guess) but I started noticing a problem with my windows PC when booting it up in the evening. I’d be working away or more likely playing games when I’d notice that the time on my PC was an hour behind the time on my phone?

So after a bit of research and learning about hardware clocks (RTC, real time clock), it turns out that the issue was due to my dual boot linux setup. Windows reads the hardware clock on startup and then uses the system clock from then on. Windows interprets the time set in the hardware clock based on local time, and so here in the UK it is UTC/GMT +1 hour (during summer). On the otherhand, when Linux boots up, it assumes that the time stored in the hardware clock is UTC and so it’s actually “an hour behind”.

Windows on Matt Ellis

Hardware clocks and dual boot