Let's play "what part is failing?"

[tw]

The one component that can cause anything inside computer to create the crash is the PSU. PSU is the foundation upon which everything else depends. However only a fool would wildly replace anything only on a whim.

You need two tools - a screwdriver and and a digital multimeter. The second is sold everywhere from Sears, to Home Depot, to Radio Shack. Even though computer fails only intermittently, the bad power supply symptoms exist constantly. You must measure those DC voltages. Those voltages must measure within the upper three-quarters of limits in this chart

Voltage   Wire Color  Min V     Max V 
 +5 V       Red       4.75 V    5.25 V 
 -5 V      White     -4.75 V   -5.25 V 
 +12 V     Yellow     11.4 V    12.6 V 
 -12 V     Blue      -11.4 V   -12.6 V 
 +3.3 V    Orange     3.135 V   3.465 V 
 +5VSB     Purple     4.75      5.25
 !Power On Green      0.8       2.0
 Power OK  Gray       >2.4 when power is good

Once power supply is confirmed by meter, then move on to other suspects.