Help needed to understand ram limitations

[BooF]

Hello all.
I recently flashed acer aspire 5735Z bios to modded 1.10 and all is well.
My small mind thought that if i do this from 1.07 then my laptop will use all 4gig of ram i just installed but it still shows only 2.9 usable in system properties.
System is 64 bit win 7 pro.
Any thoughts

EDIT: found this on youtube...http://www.youtube.com/watch?v=rDCMFEjMC7I
basically type msconfig and open go to boot section then advanced and uncheck maximum memory and restart
bingo all 4 gig used

[sukhjinderdeol]

x64 should show all 4 GB of RAM, there might be a problem somewhere!! :|