MemoryUpgrade

Hi
I have just changed my memory Dimm, from 256MB DDR (266), to 256MB DDR (333).
When my PC boots still shows at the start that the memory frequency is 266.
What changes do i have make in BIOS to get the memory frequency right?(I tried but it is a bit complicated) or shouldn’t this be done automatically?
My motherboard is a GA 8PE800 I845PE, and the processor a Cel. 1.7GHz.
Thanks
Yiotie