Bios Mods -The Best BIOS Update and Modification Source

Hello,
Sorry for my english, i'm a frenchie

I had an Amilo Xi 2528-P5210
With the bios Phoenix 1.16C
Downloadlink:
http://support.ts.fujitsu.com/Download/S...023B75B0BF&Info=FTS

And i want to use 800Mhz memory with this one...

But i don't know how i can't unlock all options of the bios

I have read it's possible because the chipset was compatible but Siemens Lock this feacture...

Thanks for your watching and your help

Hello guys nobody can help me or explain how i can make unlocked-bios ? (tools or tutorials) ?