Re: Latitude E6420 Can't find some driver!
Sometimes, due to the type of graphics processor the laptop has, memory has to be allocated from the available physical ram for it. This is most likely the reason why you see 3.88GB instead of the full 4GB. Adding more ram would not be an issue and would be definitely seen by the OS, you would just have access to 7.88 instead of 8GB which would not impact on the system's overall performance.
Hope this helps.