In anticipation of going to a 64-bit OS when Windows 7 is released I've just installed 4GB RAM into my system, previously I was running 2GB, and have hit problems trying to get FSX to run without suffering graphics corruption and crashes. The system appears to run normally otherwise and I'm seeing 3.25 GB RAM reported which I believe is correct. Before installing the RAM I had no such problems but did suffer some "snatching" or pauses when taxying in a system intensive aircraft like the Real Air Duke and sometimes AI Cessna 172s were all white.I've added the /3GB and /Userva=2560 switches to boot.ini and despite dropping the Userva value in steps of 64 as recommended here: http://www.simforums.com/forums/forum_posts.asp?TID=29041 I've not yet got FSX to run properly, although it's likely to last a bit longer with a default aircraft rather than the Duke before the graphics corrupt and /or it crashes.Is there anything else I can try before I shelve the 4GB of RAM and go back to 2GB?Software / System Specs:Windows XP Home SP3 32-bitFSX + AccelerationIntel E8400 @ 3.0 GHz (not overclocked)MSI MS-7360 mainboardNvidia GTX260 896MB2 x 2GB OCZ PC2-6400 RAM in Dual Channel ConfigurationCreative X-Fi Gamer soundcardAndy L

Not that I know of, sorry.Usually, even after installing some RAM, there >should< be no difference in performance, not the one you describe. Sad thing is, I also had problems with 4GB of RAM on 32bit system. I ended up with removing the additional RAM until I installed XP64. Everything has been more than great since then!

Check your Virtual Memory settings - perhaps you have some custom settings in there? Should be on system managed.

Thanks for the replies but having just flown for an hour with no anomalies I think I've solved it. The problem was me assuming that the BIOS would have set the memory frequency correctly as it did for the last RAM I fitted but it didn't. Found I'd been running it at 1067Mhz rather than 800, lucky something didn't go pop!The Virtual Memory wasn't system managed so I reset it but I haven't yet tried another flight to see if it's made any difference.Thanks again,Andy L