FSX is not the main problem.,,, its the OS
You cant just stick 3-4 gigs into a computer and it work
First of all, assuming the motherboard has not reduced the speed of the sticks and they are recognized correctly, the operating system must be 64bit to see and use more than 2 gigs without hacks to the boot and cache. Otherwise nothing in the system will see 2+gigs
Second, even if you have 4 gigs in a 32bit OS the best you can get out of it is about 2.6-2.8gigs of memory to the system even with the hacks.
Third, FSX will use over 2 gigs if you have a: Acceleration installed -or- b: SP2 installed, but, it requires wither a 64bit OS -or- you mark the OS wioth the hack to use more than 2GB. If you are not running SP2 or Acceleration you must MANUALLY edit the fsx.exe file using special software.
So if you are running WindowsXP x32 you must edit a line into the boot.ini file on the C:\boot.ini (requires hidden files and folders be diabled to see it) to allow more than 2gb to be used
disable hidden files and folder, then on the root C:\ you will find a file named: boot.ini
Open it in notepad and add the follwoing to the end of the OS boot line:
/3GB/Userva=2560
multi(0)disk(0)rdisk(0)partition(2)\WINNT="Microsoft Windows XP Professsional" /fastdetect /3GB /Userva=2560
NOTE: The Userva= value should ONLY be tweaked based on values which are divisible evenly by 64
This will allow you to use more than 2 gigs but you are never going to get 3-4gigs to work without a 64bit OS, more like 2.6
WARNING: setting that higher than 2560 will most likely crash the computer. Windows needs a reserve address space for the OS and video card memory mapping
Here is the MS KB readup on the line and its use
http://support.microsoft.com/?kbid=316739 In Windows Vista you must do the following:
WINDOWS VISTA ONLY:
1. Open a command prompt with Administration rights. You find the command prompt box under "Programs->Accessories->Command prompt" or somewhere around there
2. Right Click the command prompt and select "run as administrator".
3. Enter in the box at the prompt: (copy/paste if you wish)
bcdedit /set IncreaseUserVA 2560
and press enter
4. Reboot
TO set that back to default in VISTA just start the command line prompt with Admin right again and type:
bcdedit /set IncreaseUserVA 2048
Hit enter and reboot
The first value will tell VISTA to address more memory. It should be used if you have more than 2GB installed, or in some cases 2GB or less.
the second line was to restore the default Vista value if it does not work.
Make sure you have the updates from Windows Update installed that address out of memory errors too.
http://www.simviation.com/cgi-bin/yabb2 ... 1188591122 A 32bit operating system can not use much of any more than 2.6-2.8gig no matter how much memory you have installed. A 64 bit operating system can use as much as you feed it without the hacks above.