I was confused about the 20/4 pin reference. It has a 20/4 pin plus a 4 pin for the CPU. I thought it only had a 20 pin mobo connector plus the 4 pin CPU connector. I'm wandering in the dark here, I'm just learning how to mod.
Older motherboards used a 20 pin main power connector. When motherboards started using more power, first they used what looks like half of an old AT connector to carry more power. Then they went to a 24 pin connector. The extra 4 pins has one each extra wire for 3.3, 5, 12 volts, and a ground. Most PSU makers use a "20+4" main power plug with the 4 pins detachable in case you need to use it with an old motherboard.
CPU power is carried by the 4 pin, 8 pin, or "4+4" connector. This must be connected or your system will not work. For all but the most power hungry CPU's, the 4 pin connector is good enough.
Modern graphics cards are also pretty power hungry. The more powerful ones require one or two extra 12 volt power plugs. These are either 6 pin, 8 pin, or "6+2" pins. They are keyed and wired differently from the CPU power plugs. You shouldn't be able to interchange them, but it has happened. The results is a 12 volt short to ground. A good PSU will nondestructively shut itself down. A cheap PSU? Who knows?
When you are sizing a PSU, you also need to consider what kind of video card you have. A good 550 - 600 watt PSU will power any CPU and just about any video card with a single GPU.
The Fatal1ty is a pretty good, but not great, PSU.