How do i know if power supply is my problem

[Birthrulz]

Hello,
I just bought my new computer with specs,
I7 3770K 3.5Ghz
16MB Ram
GTX6600Ti
Is power supply 650w enough to power my system normally, cause im having some problems that my system is restarting when i try to run 3D mark 11

 

[ko888]

For a system using a single GeForce GTX 660 Ti graphics card NVIDIA specifies a minimum of a 450 Watt or greater power supply that has a maximum combined +12 Volt continuous current rating of 24 Amps or greater and that has at least two 6-pin PCI Express supplementary power connectors.

What is the brand and model number of the power supply unit?

 

[bigcyco1]

What psu do you have the brand and model number?

 

[Supercrit]

Cheap generic power supplies sometimes overrate the power, and most of them have weak 12V rails.