According to past experience in dealing with such problems , open it more than 10 computer Dell Studio 15  and Dell Studio 1535  chassis , the motherboard CMOS 11 discharge , after reboot still no response . Also suspect is the power supply is a problem, with a good power supply replaced , and no response , the problem of computer power can be removed to install work in the computer , the computer can work , indicating not a supply problem . But if the BIOS issue , on board CMOS discharge can often be resolved. Problem in the end where is it ? A few days ago in Internet browsing information, see a board with a black screen COMS discharge methods to solve the problem of the article , which referred to the discharge time is 30 seconds. Discharge to the board should also consider the length of time ? With doubts also reviewed some articles and found some articles referred to the discharge time , some 30 seconds , some three minutes , some 5 minutes , some 10 minutes , there is an article mentioned in the discharge time was actually two hours. The Board discharges its usually normal to only a few seconds up to ten seconds , sometimes in order to save trouble only after removing the Dell Studio 1435 Battery , the battery seat with a screwdriver to short the positive and negative a few on the line . Is it because to the motherboard CMOS discharge was too short , not fully discharge , resulting in unresolved ah ? May wish to try again . Thought here , then went to room , the computer in question to re- discharge , the discharge time of each computer full 5 minutes, bottles and after a reboot, the " tick " of a sound , the splash screen appeared, it had More than ten seconds, see the Win xp Desktop . Sudden confidence, again tried other computers on January 1 , most of the computer can start correctly , and finally, two computers can turn the power supply fan , but the display screen is still black .