I'm not familiar with the IBM hardware but in general this is what you should do.
Find out if the machine has a hardware clock and if the hardware clock is kept running by battery when you turn the power off on the server.
If you don't have a hardware clock or if the hardware clock is not kept running by a battery when the server power is shut off then that is your problem. You will either have to enter the time whenever you power cycle the machine or get a hardware clock for the machine or just live with the incorrect time.
Your boot process should include running the network time protocol daemon called ntpd or xntpd. Find out if your system is running one of these using the following command in a terminal window.
The network time protocol software will NOT reset the system clock if the system time is more than one hour out of sync with the correct time.
Make sure that you have set the network time protocol (NTP) daemon to check for the real time with a valid NTP server somewhere on the Internet. You may be able to find a time server near you on the following web page.
You can set up the NTP Client software from within YaST.