I downloaded RivaTuner v2.09 to check if my graphics card is overheated. Well, it's perfectly fine when comparing to the temperatures other people get. Anyway, so I checked the core clock speed, and RivaTuner reports it is at 632.57 mhz. Now, on the box it says that the core clock speed was 640mhz. If I overclock it to 640mhz and it becomes dysfunctional, will I be able to receive a new one from the warranty? And is there a considerable difference between the current clock speed and 640mhz, 650mhz, 660mhz, 670mhz?