You need a power supply that supports at least 600 Watts or even better a 650 Watt power supply.
That is the reason you are most likely freezing with that system set-up it is under powered.
A good Power Supply for that fix is the below linked ENERMAX POWER SUPPLY;
<A HREF="http://www.mwave.com/mwave/viewspec.hmx?scriteria=BA21102" target="_new">http://www.mwave.com/mwave/viewspec.hmx?scriteria=BA21102</A>
It has PCIe (PCI Express options for later as well if you ever upgrade your current system)
GAMERS CHOICE
What they never tell anyone much about is the DUTY CYCLE capability's of a power supply.
You could have a 800 Watt power supply but if it has no duty cycle then your screwed.
The above linked power supply has a low duty cycle meaning it will constantly feed the correct voltages to your motherboard and CPU without any power drop off.
It also separately provides power on divided channels to your hard drives, CD Rom's, CPU and graphics card. This provides power independent to all your hardware.
And it's only $89.00 bucks and better then all the $250.00 power supply's on the market
Thank me later dude!
<font color=red>GOD</font color=red> <font color=orange>LOVES</font color=orange> <font color=red>CANADA</font color=red>