Mac Flashing folder questions mark

Recently, while turning on my mac I was surprised to see a flashing folder with question mark. And I was not able to log in to my system. So, I started investigating the cause of this problem. And there may be 3 causes:

1.Damaged HDD connector.
2.Corrupted HDD.
3.OS has been corrupted.

In most of the cases it is the HDD connector which got damaged.

So how can you check that one ? Well, If you have an external hdd connector, then you can open your mac HDD and connect the same externally.

  Now, if your system boots up, then its a problem with your HDD connector. If you still have the same problem, try                  connecting the mac HDD to another machine (preferably linux) externally and check whether your file is showing or not if you   are able to see any file then your os has been corrupted. Otherwise it is a problem with HDD.

Keeping your mac cool

RAM size increase

keeping your mac cool

smcFanControl controls the fans of every Intel Mac to make it run cooler. smcFanControl lets the user set the minimum speed of the build in fans. So you can increase your minimum fan speed to make your Intel Mac run cooler. However in order not to damage your machines smcFanControl doesn't let you set a minimum speed to a value below Apple's defaults.

What's New
Version 2.4:
Support for OS X 10.8 Mountain Lion / Gatekeeper
Support for Retina Macbook Pro
smcFanControl is now a 64 Bit application
AutoStart works now without AppleScript
Support for Mac OS X 10.4 is deprecated
The source code for smcFanControl is now available at Github