I currently have to run FSX on medium low settings to run it smoothly. Here is a rundown of my system where is the bottle neck?AMD Athlon 64 X2 Dual Core 5600+2.81 GHz3.5 GB of ramGeForce 8800GT

It is not possible to really say what the bottleneck is for certain, if indeed there is one which could be sorted, without knowing the motherboard type, what bus speeds it supports, and what type RAM you are using and the RAM's speed. Post that info and people will be able to have a better shot at advising you.At a guess, I'd say the RAM might be the guilty party (and it is only a guess without knowing its type and speed), for example, a computer with one Gig of DDR 3 RAM installed on a motherboard with bus speeds that support it fully, will likely be faster than if it had 4 Gigs of single data rate RAM with a low clock speed on that same motherboard.You can find out all that info by running a little utility called CPU-z, which you can find here: http://www.cpuid.com/cpuz.phpAl

Also, what do you consider smooth, where do you fly, and are you running anything else? My default FSX runs at about 35 fps under most conditions, with the sliders at around 3/4 up, and my system is roughly equal to yours. You can always turn off bloom, turn down traffic (ground, water, air), and turn down the water for the biggest increases in framerates.Jeff ShylukSenior Staff ReviewerAVSIM

I'd remove that 512MB stick of RAM. The OS really doesn't like "oddball" RAM like that... :(

Easy. The bottleneck is the whole system....You're system is similar to mine, and our CPUs are outdated and I get similar performance but I have things tweaked as much as possible.Be sure to read this post regarding tweaks:http://www.simforums.com/forums/forum_posts.asp?TID=29041