So then the question becomes if fsx spots more ram is available, does it use it? Right now I run around 90% of 1.5GB. If I were to go up to 3GB would I just drop to 45% used or stay at 90% with improved performance.

Here it is: Nothing exotic :)Dell Gen 3 P4 3.4 (Prescott Core)3 Gigs of Crucial PC-4200 (533 MHz)ATI X800XT 256 meg video cardAudigy 2 Sound card 5.1Samsung 931BF 19 inch LCD 2ms.BTW, XP with a few background's on my system eats up 1/2 a gig!I have to tell you...with three gigs now, my system screams!My MEAN AVERAGE FPS now is 18 FPS. It does go to 20 (rarely) and drops also to around 14, again rarely now. So 18 is a good mean average 'steady' for myself. Before I did a memory upgrade, I got 12-16 with everything on bare minimum, and NO Auto-Gen of any kind.To say that I am now thrilled...would be an understatement. I paid $257.99 (USD) for the other two gigs. Mitch

XP has a 2GB per process limitation. Since FSX runs in a single process, it will never be able to use more than that. Unless you're running on 2003 Server and enable the /3GB startup flag to enable 3GB of process space... Wish I had one of those to play around with.

I guess that I'll have to grab memtest and see what gives. I would think that a program that is loading textures at the rate FSX wants/needs to, that it would use every gig of RAM it found, less the reserve that XP takes for itself.It stands to reason, why wouldn't it? Why would the program leave memory available to XP non-addressed?You bring up a good point, though.I noticed no true difference adding another gig to my one. It was when I went to three, that everything happened for me.Unscientific, yes...but undeniable for my system. That is what elicited that 'MY GAWD' exclamation this morning. I went from 'I need a new system, to say WHAT?' :)No new system for this lad. I'm happy with the 18-20 with all the important sliders to the full. FSX at 18 to 20 is very doable.The ones to ask about how much FSX will use system resources available to XP would be the ACE team. If any of them are reading my threads, it would be nice to hear back from them. :)Mitch R.

something is wrong with your memory reporting tools perhaps? my "xp with a few backgrounds" stays around 200 meg

I'm running Norton's full suite, a Gamma setting program, ATI, and a few others. I found that when I all deleted from the background before the addition, their departure really didn'at add up to any true FPS gain.With the 3 gigs now, nothing brings down the 18 (for extended intervals) at present. BTW, that's at detailed airports as well. Like I said, I do drop to 14 rarely, and only for a split second. Perhaps that is a CPU cycle call? Dunno... :)Mitch R.

That is good news it seems. I have 2 gig and by using FS Autostart and killing most processes the mem utility shows 1.7 gig used when running FSX. My video memory used is 245 meg on a 256 meg card. I would be interested in the verification that for any single instance, XP only can only use 2 gig. I would jump on more memory in an instance if we could get some solid verification.RegardsBob

Given that other people are reporting that 1.3GB is the 'normal' operating load for FSX plus background system jobs, I wonder if the first GB made the biggest difference (to allow for the missing 0.3 GB). I would be interested to know if FSX is using the 3rd GB or not.I ask this because I have 1.5GB of RAM with an AMD 64 3700+ and an ATI X800 card. I'm getting reasonable performance with this after a few tweaks. Mitch's post has got me curious about ordering more RAM, but I think I need more data before I decide...Mitch, did you add your RAM all in one go or did you test it incrementally? If you added it incrementally, I would be interested to know what the step up in performance was like.

Hmmm this is an intresting post. I would like proof myself. I have 1gb of ram the only problem I have with frame rates in general is when FSX hits the hard drive after its though the FPS are ok again.I know I need some more ram but is 2gb to 3gb more really needed?

1.3GB used according to memstatus for me

I'm far from an expert on this, but my understanding is that having 3GB allows the operating system to access the extra ram freeing up more for FSX to use.

My system has never used more than 1.6 gigs according to Task Manager. But then, we must all remember that some data is being put into the swap file. So, the jury is still out...perhaps 3 gigs does indeed help, perhaps not with all configurations. It's an interesting question to be sure, and one that I would like to hear more about from others.RhettAMD 3700+ (@2.5 ghz), eVGA 7800GT 256 (94.47), ASUS A8N-E, PC Power 510 SLI, 2 GB Corsair XMS 3-3-3-8, WD 250 gig 7200 rpm SATA2, CoolerMaster Praetorian

This is off a memory forum I found.With 32-bit systems, the maximum addressable memory is only 4 GB, of which a maximum of 3GB is actually available to applications. They also said that if you wish, they only said wish with no actual validation, but if you wish to go above 3gig, there is a switch or registry entry that will allow ram above 3g to be used. Still investigating. Even this proves to be fruitful at the os level, we still need to know if there is any limitation on addressable memory for any given application.Bob

Here is some interesting stuff:Although the maximum addressable memory in the 32-bit world is 4GB every process running in 32-bit Windows XP normally have access to at the most 2GB us memory for its own use not matter how much RAM memory there is in the machine as the other 2GB is locked away for the systems' internal use. The scenario in the music world where we're likely to encounter this limit is when using software samplers and plugin hosts hosting software samplers where lots of data needs to be loaded into RAM memory. Microsoft also acknowledged this problem and created a way to circumvent this problem, at least partially. By using a combination of an option in the boot configuration and an application capable of detecting this option if possible to push the limit to 3GB thus leaving 1GB to the system.The boot option is easy to set by editing a simple file, but the problem is that not all applications we're using have support for the option. Due to the ingenious design of this feature however it's possible to make any application aware of this option without having access to the source code or having to rebuild the application.There are a couple of tools out there that are capable of doing this, but they are all directed to developers and not end-users as end-users are not normally supposed to fiddle with these things. Nothing could be more wrong when it comes to the memory hungry music community! In order to provide an easy-to-use tool which contains some additional safety measures I wrote LaaTiDo, the LargeAddressAware Editor.DownloadLaaTiDo is available for download at http://www.musikbanken.se/laatidosetup.exeInstallation and operationRun the installer and follow the instructions for installation. Read the knowledge base section below to find out if you're affected by any of the issues listed there.Expected resultsOn a 3GB machine you can expect to be able to use up to about 2.7GB for a process. On a 4GB machine the same number is about 2.9GB.Knowledge baseEnsure that you have Windows XP Service Pack 2 before adding the /3GB boot option. Boot problems causing the machine to fail may occur if Service Pack 2 is not applied on certain machines. To avoid the possibility of a mistake regarding this, ensure to follow the guidelines and copy the line in boot.ini. Samplitude which is currently not LargeAddressAware is not possible to patch as the copy protection checks the exe file for every single bit change.. LinksI wrote an in-depth discussion on the topic for Virtual Instruments Magazine and it is available in the June/July 2006 issue. I also wrote a guidelines post for Vienna Symphonic Library regarding memory configuration in relation to their Vienna Instruments line of products. Microsoft MSDN article on LargeAddressAware. Microsoft MSDN article on /3GB Last updated: June 22, 2006

Well I'll try that for sure... one GB extra might just do the trick for FS it seams. Anyway for this old AGP system of mine.And for those really really hungry for memory... how about put your swap file in your 2nd _physical_ drive. specially those with WD Raptors and all. Free up a 2Gb partition and send your swap in. don't use it for anything else. Label it XPSWAP or whatever. OS should work better too, don't forget to disable previous SWAP you had. reboot!details just ask...regardsPedro