i m using window 8 on my desctop having dual core, 2.5 GHz, 250gb hd, 2 gb ram, and lg dvd writer.now a days my pc has rough sound during starting up. after start up it is not there. after start up the pc my SMPS (power supply) fan remains on but having no rough sound. i have cleaned my motherboard, microprocessor and SMPS fan etc also. but no result. kindly help me. thanks in advance.