Cant go above 3.8ghz

Sorry, cheti, it looks like you may be reaching the max overclock for your particular cpu - even amongst identical processor model numbers, not every cpu overclocks the same.

However, have you done the usual googling using your cpu + motherboard model numbers?......chances are that others will give you more ideas for settings that might improve your overclock. Be very carefull in doing this - you don't want to fry your cpu!

A quick google (just overclocking your cpu and suggests you might get higher):-

http://www.overclock.net/t/1281342/fx-8120-overclock-he...
http://www.overclock.net/t/1226595/need-help-fx-8120-ov...
http://www.tomshardware.co.uk/forum/269874-11-fx8120-ov...

You must lower your memory multiplier having in mind that

fsb x multiplier = value that is in the range of your memory can run.

For example you can run the fsb in 800 and if the multiplier is 2 your memory will run at 1600 is in the range.

Then you set your cpu host x value that you can handle the heat and the voltage.

If your motherboard doesn’t support lower value for the multiplier you can’t solve the problem easy.

yeah, my memory is 1600mhz which is achieved by 8x multiplier, my fsb is 200 (auto) and my cpu multiplier is 19.

But whenever i go above 3.8ghz, my memory gets unstable and i get random bsods.