It is obviously dying or incapable of supplying a sufficient flow of power to the system. Before it blows, you will want to buy yourself a new one to prevent losing other components within your system. You can find some very good power supplies at
this website. Once the page loads, search for: PC Power & Cooling. After the page loads, select, "PC Power & Cooling" on the left under the category, "Manufacturer."
Make sure you find one that exceeds your power needs by about 100-150 Watts. Yes, they are expensive, but you DO NOT want to skimp on the most important aspect of the computer, power. Wen it comes to power, you get what you pay for. Almost all cheap power-supplies will last you one year and then blow. And once they blow, they frequently take other components with them. Components such as motherboards, memory, CPUs, and Video Cards.
The reason behind picking a PC Power & Cooling PSU is rather self-explanatory. Firstly, they have the highest efficiency rating of any single-rail PSU. Secondly the PSU tends to run cool, thus increasing its life span. Thirdly, they are reliable and provide a steady flow of power. All of this equates to a great power supply which will support your system for a
long time.
Let me know if I can assist you further or if I need to explain anything mentioned above in more detail.