How do you overclock a ATI mobility Radeon HD 4200?

Answer 1

Download AMD GPU TOOL and increase the core clock by increments of 5Mhz then stress the GPU with a benchmark tool like 3DMark 2006 a few times in between until you reach the maximum overclock, once you reach it the screen should freeze and the laptop will shutdown or freeze, if it freezes take out the battery and turn it off and let it sit for about 30 minutes to cool it down, next you need to turn it back on and drop the clock a stable one, for example most HD4250's can run at 700Mhz but its not stable, drop it to 650 and test at that speed with something like ATI-Tools artifact scanner for about 3 hours.

if its stable then you just overclocked your laptop

never try to jump up the clocks while testing though, never jump from 500 to say 600 and test, that's the easiest way to damage the laptop.

remember if you do damage it, its on you.