Are you running a 64 bit OS?If not, you should..6 GB should be sufficient for FSX, but agree with Paul above on keeping it symmetrical.

Yes, Paul, it is a typo. It is actually a 2600K. The OS is Windows 7 32 bit (that will change next week). When it runs out of memory, It says that FSX has run out of memory and will have to shut down, which it instantly does.I believe the info you passed on to me concerning the RAM is old history now, Paul. We can use most any combination of RAM nowadays - 2 GB sticks, 4 Gigs, mix and match, whatever we choose. It is no longer necessary to use the matched combinations that used to be required.To Bert Pieke, I do have a 32 bit system, but it will be 64 bits very soon, along with 16 Gigs of RAM. I expect to see some real improvement then. Who knows? I may even be able to max out my Level of Detail Radius once I do that!I'll come back and post the results of the upgrade to 64 bits and 16 Gigs of RAM next week.Thanks to both of you for taking the time to respond to my post. I hope your Thanksgiving was a good one.Dewey