By increase disk size...

[quote]When I tried to start the PC, the fan on then off immediately.
[/quote]
CPU fan or all the fans inside your case?

[quote]I tried to increase the primary master disk from 60GB to 80 GB, the problem occurred again.[/quote]

By increase disk size from 60g to 80g do you mean by replace it?

650W power supply is more than enough for your set up, and most IDE HDs are not power hungry as CPU/Graphic card does.