Computer locks up viewing/editing hi-def videos with new Intel i5 CPU

I just got the Intel i5 CPU and a full-sized Gigabyte mobo. It replaced an older AMD Phenom. I had no problems watching or editing high definition videos before switching over to the new Intel cpu and board.

Now when I try anything with hi-def, the computer locks up and I have to do a re-boot.

I have a few questions.

I have a good name brand 600 psu. It had just the 2x2 molex for the power supply connector for the mobo, which has the 2x4 molex. I can connect the 2x2 in part of the mobo power supply connector. I tried that and no difference. I then got a 2x2 to 2x4 adapter for the motherboard but still no difference.

So, I am thinking about buying a newer 700 watt psu which has the 2x4 molex plug for the mobo power connector. Will that make a difference?

What makes it worse is that before switching to the Intel i5, I first moved to the Intel E8200, which worked fine. The Intel i5 is a much faster processor, plus it is quad core, unlike the E8200, a dual core. BTW, having a quad core is nice.

I can't find anything anywhere that says anything is wrong with the i5. Would there really be a different switching from the E8200 to the i5, which really is a much slower processor.

Any input would be appreciated.