Likely a cooling fan issue. I too had similar issue on my pc. Better get it checked now else, a time may soon come where the fan components may get burnt out and your pc may not start at all.
Worse, there may be a problem with your HDD(through not very likely), however since we traders depend heavily on our data, it would be on the safer side to have a backup of all your data. software, tools, etc. esp which you use for trading.