Specs: Core2Duo E6600, 4 Gb OCZ RAM (800MHz), Nvidia 8800GT (512Mb), Win XP Pro SP2, FSX with Acceleration. System properties shows RAM as 3.5 Gb (as expected).I have boot.ini set up with userva=2650, and have checked FSX.exe with CFF Explorer to confirm that "App can handle > 2Gb addresses" (which it is automatically with Acceleration). Here's how the end of my boot.ini line reads: "/noexecute=optin /fastdetect /3GB /userva=2560"And yet, when I've got FSX running on one screen and Task Manager open on the other, FSX never seems to go above 1 Gb in the "Mem Usage" column of Mem Usage.My paging file size is initial 4092 Mb, max 6138.I don't see why FSX isn't using more memory, even with 1m photoscenery and lots of autogen. My sense is that I should be able to achieve smoother performance than I'm getting...

Ya got me Dave....I've done everything you have (except SP1, no acceleration), my boot.ini is the same. I'm flying right now....just checked...and I'm using 1.7GB of RAM, have a nice 'ceiling' left, and this baby is running 'smooth as a babies....' well, you know what I mean ;)