Vista 64 8GB DDR2 Only 3GB Showing.

[Discovery821]

Hello guys,
I got a Sony vaio fw11zu upgraded with vista ultimate 64bit, HD WD Scorpio Black 750gb 7200rpm and 2 slots DDR2 800MHz (2x4gb) SODIMM Corsair. I got the following situation:
CPU-z test = 8gb
Everest Ultimate test = 8gb
BIOS upgraded = 8gb
but
Taskmanager = 3gb
Msconfig upgraded but still says = 3gb
Properties = 3gb
Also I have download Hotfix (MSinfo32.exe) but still detected only 3gb
Personally I agree with free682 that the machine is using the full amount but just shows 3gb
Any other ideas?

 

[unreal9400]

How did you manage to install 8GB?
It says here max memory supported is 4GB RAM.
http://www.sony.co.uk/support/en/product/VGN-FW11ZU/specifications