Sadly for me it wasn't every time that my computer came under heavy load. Sometimes it was due to watching a movie on my computer. I think what it boiled down to was the gpu/cpu power draw was too much draw for the PSU to output on a consistent basis.

There are ways to test for it, but they usually require voltage meters. I guess the easier thing would be to list your specs and list your PSU.

Another thing I heard that worked for some people was downclocking their cpu and/or gpu to reduce the power draw.