OOM errors kind of figured out

[Guest Callmecapt]

Ok, now I'm no computer whiz, but after helping out an online vatsimmer with his FSX ( he couldn't get it to work without freezing up on him. He has a 7300LS Graphics card I think and 2GB of RAM) I decided to do some experiments based on what I read in the forums and on what he said about his system.I tried the 3GB switch, and although I got it to work with FSX and FS9, it locked up Battlefield 2142 after 5 seconds of playing. I think I read that the exe file has to be modified for the 3GB switch for it to work. Hence, BF2142 didn't work.Ok, reboot to the original configuration without the 3GB switch and BF2142 works again. So I decided to do it properly. If XP only uses 2GB of physical RAM, I decided to remove 2 GB from my PC and leave 2GB in. Restarted the PC, restarted FSX, and OH MY GOD!!! Any jerkier and it would be a slideshow.I turned off the PC and put in 1 more GB and restarted everything. A little better but not by much. Still averaging about 12fps in outside view.Restored it all back to 4GB WITHOUT the 3GB switch, restarted FSX, and back to a smooth 35fps in outside view for the 747 and 25-30fps in 2D cockpit WITH lightbloom selected.I have had an OOM error 3 times since buying FS9 and installing 4GB of RAM. Twice it was approaching Aerosofts Heathrow.A little addition. I'm not disputing the fact that XP doesn't use all 4GB at once, but maybe it shuffles it around and uses as much as it can and the rest is reserved and ready to use. Something like that.Anybody more tech savvy care to help me out with this one with a little bit of elaboration?My system specs:XP SP38800GTS 512MBE6750 Dual Core4GB RAMI also have O&O clecer cache installed.Goran

[Guest Erups]

It really goes like this.Memory is a limited resource and is needed by both applications and the operating system (with all its bells and whistles).32Bit operating systems may only address 4gigs, so this is the maximum amount of memory the system can use.Now onto the actual use.Windows XP (and 2000,2003,2008, vista and all Unix-s and maybe even more) defines two large areas of system memory: reserved and user available (referring to system-space and user-space).Reserved is used for its inner workings, while user memory may be requested and used by applications.Now this is where the 2GB limit kicks in: each and every application may have a maximum amount of memory in use of 2GB.3 with the 3g switch.That's all.Now why WinXP is reporting less then 4gigs, or what else is it doing with the hidden amount may be interesting questions, but they do not shed light on this particular subject.Maybe Vista has a kernel able to better handle big memory loads, but the basics behind it are the same (or slightly improved): no process (read: application) can have more then SOMEAMOUNT-GB of memory allocated, as some of the rest is needed by the system.The reserved amount variates with the installed amount, processes handling policies, OS inner workings.For example you could see a difference if setting your WIN on "background operations" as the memory priority in the control panelsystemadvanced dialogue.Anyway what all this boils down to is: more ram is better then less.