gigabyte p55-usb3 and bios

Hi

i have this mainboard : gigabyte p55-usb3
i have some difficults to install win xp pro and recognize the memory (
4096 and it recognizes only 3,4)
So i was with bios F2 and i ve installed bios f4 ( downloaded on the
server of gigabyte )
for install this bios i've used @bios and file downloaded in my
personnal docs
But now , my computer reboot and reboot and reboot etc...........
impossible to load new and old bios

how resolve this big difficulty ?

thx at all