I have a three year old system with 4GB RAM installed. It was running great with my overclocked nVidia 8800GTS with 320mb memory but it bit the dust. I decided to up grade to a 9800GT with 1024mb memory to increase the performance and now FSX is pausing and stuttering badly. I was told that this is caused by the 32 bit operating system only recognizing a total of 3.2 gb of total memory even with the 3gb switch. My understanding is that because the video card has more memory than before that it is causing my RAM to shrink in usable size by the amount of increase in video ram. I think I am explaining this correctly but am not sure. I was also told the only solution is to upgrade to a 64bit operating system so all memory will be used. It was explained that I fell into the common trap many do thinking that they were increasing the performance of their computer only to find the opposite using a 32bit operating system. bummer

What's happening is with the onboard 1 GB of video ram on the new card is that your 'AGP aperture' has now also automatically increased proportionally as well. Basically, the MORE onboard video memory your video card has, the MORE your motherboard's BIOS/Windows XP 32 (one of the two or both?) automatically reserves for texture memory swapping. Your new 1 GB card does not actually need to reserve ANY texture memory in your system's main RAM for swapping now, but this goofy Windows XP 32 design automatically reserves it anyhow and will now reserve even more main memory than with your old 320mb card. Since you're running the 3 GB switch with Windows XP 32, your system divides up a max of 1 GB for the Windows operating system and the other 3 GB for any application you are running, including FSX. Unfortunately, your system is now also forced to share the 1 GB of Windows operating memory part with the now automatically increased video texture swapping memory reserved part (again the so called, 'AGP aperture'). There is basically not enough memory in the 1 GB part of your main system memory for both the Windows operating system memory reserve and the now way over-bloated video texture memory swapping setting (all this with the 3 GB switch enabled). End result - massive stuttering and screwed-up rendering in FSX, making it useless.The fix: simply disable the 3 GB switch in your boot.ini file. Problem solved. With the 3 GB switch now disabled, Windows XP 32 will automatically reserve a full 2 GB for Windows itself and the other 2 GB for FSX or any other application you run with your 4 GB system. Plenty for both under normal circumstances, and you won't have to worry about all the extra main system memory that is essentially being wasted by the AGP aperture (texture swapping reserve). Motherboard BIOS setup utilities used to have a dedicated AGP aperture setting that you could manually control to avert this sort of thing, but with advent of PCI-E (in place of the older AGP) standards, this setting has seemingly disappeared altogether that I know of. The only way to get around all of this krap though is of course to upgrade to either Windows XP 64, or even better, Windows 7. Both of these operating systems will automatically make full use of ALL of your main system memory in an intelligent, well designed way. Windows XP 32 was never really designed to efficiently use more the 2 GB of ram, unfortunately, so the 3 GB switch concept was truly a stopgap fix at best.

Aaron, Thanks for the heads up on the 3GB switch fix. I am going to try it. I thought the 3GB Swiltch was a fix for larger memory usage.

The 3/g switch is usually considered as a fix for OOM errors. If you get OOM errors after disabling the /3g switch then put it back and reduce the USERVA value.

The 3/g switch is usually considered as a fix for OOM errors. If you get OOM errors after disabling the /3g switch then put it back and reduce the USERVA value.

Thanks for the heads up. I have disabled the 3GB switch and the stutters and pauses have stopped for the most part. So far I have not had a OOM but my fingers are crossed. Both Aaron and yourself have helped me a great deal and now I hope I can get back to flying. Norm Flowers Southern California's largest flight simulation group, www.simflite.com Please contact us if you are in our area sometime. Thanks again.......