After a look through the bios once more I found what I was looking for, one line of text reading Appropriated 640mb lead me to find that my board does not have support for memory remap, asus have never released a bios that supports it.

So it look like I need a new motherboard before I can make use of all my memory.

Thanks for the tip, unfortuantely it did not help.

Only thing I was able to find quickly and since I didn't know what exactly to searh for was make Win7 x64 use all your mem…. Unfortuantely that did not help me, the option it says to uncheck was already unchecked.

Hopefully someone have an answer to this.

I've just installed the RC 64bit to see what all the fuss is about, but yet all my memory is not being used.
It's like I installed the 32bit version, the info windows say 64bit operating system but only show 3,37gb (4,0gb installed)
So for some reason I don't have all the memory available eventhough I should have.
Anyone kow what could be the cause of this?