How to know if a Power Supply(SMPS) is failing?

Aromal

Private Rank 1
Messages
33
I think I have some issues with my 450 power supply of my PC. My Hard disks will frequently turn off and on and I can hear the read/write header scratching the disks at that time. So how can I find if my SMPS is failing?
 

Arjun Chandran

Master Sergeant Rank 13
Messages
622
When my power supply was about to fail i used to hear some click sounds and flashes.Sometimes my PC won't power up at first try.