Okay I just want to ask would FS run fine with 4GB 1600MHz ram or is it necessary to boost 8GB or more to run FSX.I currently have an I5-2500K and a GTX 550ti 1GB card.running the i5-2500K at stock speeds right now, I have to go out and purchase the Hyper 212+ .

1st item is the stock cooler should allow you to overclock to about 4.3. FSX does not even use all of 4GB so you are good to go.

This has been a hotly debated subject in the past, but with the way memory prices have dropped recently, you really can't go wrong with 8GB of memory. It's a good way to ensure FSX gets the full 4GB of memory to which it's entitled (even though it often doesn't need it) while greatly reducing the risk of any potential OOM errors. BUT, many are running 4GB with no problems at all.

Wow thanks for the input and yeah I see why not just spend 36 more dollars to buy another two sticks of ram. Also is it really possible to go to 4.3 ghz with the stock cooler, I can't imagine it being safe for the CPU. But then again what do I know :). Should I try and Overclock it on the stock cooler ? I have a biostar T+Z68 board and overclocking is a breeze.

Read about over-clocking HERE 6Gb RAM should fot using 64bits OS W732 bits only addresses up to 4 Gb RAM

If you run addons such as GEX, REX and UTX such as myself, you will see FSX get up to near that 4GB mark so OOM's will be likely at this level, so 8GB is recommended.

Alright I got this ramhttp://www.newegg.ca/Product/Product.aspx?Item=N82E16820231455The speed is fast too so I think this will work.