Sorry mate, that system ain't gonna run FSX on high settings.
For high settings you need:
Intel Quad Core @ 3.5GHz+
Your graphics card should be good enough though.
I've got a 4.3GHz i5 3570K and 8GB of RAM, and I STILL get lag on FSX.
It just shows that it's so far impossible to actually max out FSX without having any lag.
Your PC should be able to play FSX on medium settings quite well though. You would also have to be careful about what your traffic settings are. Anything above 50% and your framerates will really plummet in busy airports.
i5 3570K @ 4.3GHz, ASRock Z77 Pro3, EVGA GTX 670 FTW, 8GB DDR3, 128GB Samsung 830, 500GB Seagate Barracuda, Thermaltake Armor A60, Logitech Extreme 3D Pro, Logitech K800, Logitech M510, Windows 8 Pro x64, FSX Acceleration