ram problem -- really strange

hi there
i am installing windows seven 64 bit
and i had 8 GB of ram installed the os reads them well ----> it shows 8 Gb of ram
but when doing a heavy processes like rendering in 3ds max
it only use 3 Gb of ram and the rest acts like free ram space --------> i know that from the Performance Monitor
that is making me crazy as i want this processes to use all the 8 GB
thats why i payed for it


Anyone knows whats going on here? --- thanks

[EDIT] Removed for irrelevance.

thanks for your reply
but,
the program some time closes because the scene is very huge and need more ram
and specially this is making me crazy
as it needs the ram and it is there but can't use it

Ah I see. I misunderstood your problem.

Is the program you are working with a 64bit version or is it a 32 bit version running in a 64 bit environment?

no it is 64 bit program

Check your Bios, some have options such as 'dynamic memory remap' , enabling or disabling may help.

Also if you go to run and type in 'msconfig' ,hit enter and goto the boot tab>advanced there is a box for maximum memory you could set it for the full 8GB and then re-boot. I don't know if that will work though.