MSI MS-7293 ver 1.0

[crazy4bios]

i have this mb : MSI MS-7293 ver 1.0 from fujitsu siemens scaleo p ms-7293.
all go well except tha amount of ram.
i've installed 2 corsair xms2 ddr2 800mMHz, 2gb each so 4gb total but in the bios only 3gb
in windows 10 x64 say 4gb, usable 2.94gb : i heve gforce 7500LE so no ram shared with windows.
so, O.S. see the 4gb installed the bios no.
i downloaded 1.30 overclock version and i flashed the bios but always the same : only 3gb.
could you help me to solve this problem ?....or try to change same values on bios ?
so i ask unlock request for msi ms-7293 main board, to view all 4gb i've installed

this is my bios info:

BIOS Vendor Phoenix Technologies, LTD
BIOS Version 6.00 PG
Firmware Version 111.101
BIOS Date 12/21/2006
BIOS Size 512 KB
BIOS Starting Segment E000h
BIOS Release Version [unknown]
DMI Version 2.4

please help me thank you