I had a FX 8300, was a good cpu in it's day but it's 32ns tech is just not able to do what the new 12ns and 7ns tech CPU's can do. It just cannot process the info quick enough and then throw DDR3 RAM into the mix and there you have your bottle neck.
Overclocking the FX 8300 (is it the Vishera ?) which I have done is not a big help as they run very hot due to the voltage increase needed to get anything meaningful on what is already a power hungry CPU so you will need a very good cooler.
To compound that the MoBo you have will be pretty old and may well not be able to handle the stress of the overclock and blow the Virtual Memory Controller or something else like a RAM slot....
The GPU is also boarderline for this day and age but it...