i have an old pc using pentam-4 2.3 ghz, 256 mb ram 7 years old. it runs fine but it some times just paused,sometime show a overheating message and it keep restarting. cabinet fan is not working so i opened the cab side panel but problem still happends sometimes. i belive it is the problem with the overheating. how much it costs to fix it? what should i do to fix it? replacing the fan? replacing the procy fan?