In my previous post I have finally find the solution to my HD 4870 “click” issue but have another worst problem and it is the clock, my ATI Radeon HD 4870 XFX XXX 512 is overclocked by the manufacture with 775mhz of GPU clock and 950 of memory clock but the clock when I don’t use the ATI Overdrive is 200mhz and 500mhz and this clock continues in 3d applications but normally the 2d and idle clock is 500mhz and 950mhz now I’m using the ATI Overdrive but have another problem and this problem is the GPU fan because the fan can’t up automatically only with manual fan control