Current PC specs:

 

 

ASRock Z77 Extreme4

  SilverStone ST75F-P 750W PSU Gigabyte GeForce GTX 670 OC 2GB Video Card Intel i5 3570K 3.5gh Samsug 840 Pro Series 256GB Corsair Vengeance CMZ8GX3M2A1600C9R 8GB (2x4GB) DDR3   Cooler Master Hyper 212 EVO CPU Cooler

 

current average FPS in FSX: 15-25 (worst case)

 

lots and lots of addons installed

 

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I'm looking for some advice on:

 

1. Whether I should overclock my CPU and what ghz should i aim for?
2. How bigger increase in FPS will i receive?
3. Does anyone have any easy guide on how to OC for my pc setup?

 

 

 

 

1.I'd think you could hit 4.0 GHz easily.

2. Maybe 5 at most if you go to 4 ghz

3. Here's a guide on intel OC 

I have the same CPU, OC'd to just 4.3g and coupled with the rest of my stuff listed in my profile, I get very decent performance.

That board should have an overclocking section in the bios. I have that cpu comfortably running at 4.4 on air. It does make a big framerate difference. Certainly worth doing and the 'K' series are made to OC. Check if you have the ASRock’s overclocking and hardware monitoring utility, which allows users unfamiliar with or scared of UEFI changes to attempt an overclock within Windows

http://m.youtube.com/watch?v=668ATnnBOZU

 

This is an excellent guide and uses an Asrock MB with a 3570k. It also uses the "offset" method for setting your core voltage with "speed stepping" enabled, a method I strongly recommend if you are worried about the effect on your CPU's life due to overclocking. This method basically under volts your CPU when you are not puting it to use (idling for instance).