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"