On this new PC I have 4 GB but windows only uses 3.69 with a x64 system. Maybe it's because I'm using and onboard graphics (from my CPU I5 3450 3.1Ghz ~ 3.5Ghz)
That's certainly possible.
I honestly never have completely figured out WEI, but it's basically useless anyway, so I just haven't felt the need to waste my time trying.
There are tons
of other reliable and trustworthy benchmarks, and you can generally get a "feel" for how everything is performing without them anyway. You shouldn't really need a useless thing like WEI to tell you how you system is performing.