Windows and your graphics card drivers are up to date?
Maybe try a powered USB hub? Just to eliminate that as a possibility. Before doing that, look at the USB terminals inside your case because some USB terminals coming off the board power more than one external USB connector. I have seen up to four USB ports being powered by one motherboard USB port. Make sure your USB loads are spread between the motherboards USB ports.
I think you may want to check your voltages when you computer is under a load. You can do this with a multimeter while doing a stress test. Check all three voltages at different places, especially check the 12 volt connector at the graphics card. Install a stress test for your graphics card along with Memtest 86 and Prime 95. You have a really good PSU so that's a bit baffling. But test it anyway.
A power surge is when the voltage spikes, not drops. It is an inaccurate term because power and voltage are not the same thing. One thing a voltage spike can indicate is that your PSU is either inadequate or going bad.
Don't overclock anything until your computer is working correctly and is passing the stress tests. I think that is pretty obvious.
