Typically, BIOS should use UTC clock, and system clock should be working depend on ../Timezone setting.

However, there is a difference when we have one of Microsoft's operating system on our machine. They set local time also in BIOS.

To avoid differences between Windows and Linux edit /etc/sysconfig/clock and set:

UTC="false"

If you have only PLD Linux (or PLD Linux and other *nix) set:

UTC="true"