hello, 

I have radeon 6990m.

windows 7 home premium 64 bit.

tried on 13.1 and 12.8

2nd Generation Intel® Core™ i7-2720QM Processor ( 6MB L3 Cache, 2.20GHz)

2nd Generation Intel© Core™ Chipset HM65

I thought it wouldnt be so stupid to try and overclock by just 10Mhz..I was wrong..

now every time i start my computer i get black screen after windows logo.

I tried to go into safe mode and disabling the adapter, go back to normal mode and remove catalyst ith all the drivers using DriverSweeper and reinstalling everything back.

still no luck.

is there any one who's familiar with this problem and can help me?

**I posted this at "laptop" but i think this is a more suitable place

You can try edit profile, that contains high clock, search for that in folder "C:\Users\Username\AppData\Local\ATI\ACE\Profiles"

Coreclocktarget is your point.