Is this a decent PSU for my homebuild?

Judging by the chosen parts it should be okay if you can't afford anything else, but you MAY want to upgrade a little to add headroom. Fans generally don't draw large amounts of power.
 


I will be overclocking my CPU, do you mean OCing GPU, I won't be doing that. If I can OC to 4.2 Ghz then I'll get this PSU, but I will probably upgrade in the future if I want to crossfire (not for a long time).

Thanks everyone 😀
 

that seems a good psu to look at but no chance of crossfire as your card needs a 6 pin and 8 pin pci-e power connector and it has exactly that so the cheapest good psu you can buy with the right wattage and connectors
 


For a system using a single GIGABYTE GV-R797OC-3GD graphics card GIGABYTE specifies a minimum of a 550 Watt or greater system power supply. The power supply should also have a maximum combined +12 Volt continuous current rating of 33 Amps or greater and have at least one 6-pin and one 8-pin PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.

Overclocking of the CPU and/or GPU(s) will require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted. Since your CPU overclock will be less than 4.6 GHz there's no need for an additional increase.

The XFX 550W Core Edition Full Wired (Bronze) (P1-550S-XXB9), with its maximum combined +12 Volt continuous current rating of 44 Amps and with one 6-pin and one (6+2)-pin PCI Express supplementary power connectors, is more than sufficient to power your system configuration with a single GIGABYTE GV-R797OC-3GD graphics card.
 

wow you really are a psu master much better than my comment
 
Wow, ok I didn't understand most of that ko888 but, as long as the PSU is sufficient.

Andk kammak, what do you mean there is no chance of crossfire with my card, it's like in the top ten best radeon cards.
 
Oh right, ok that's fine. I might crossfire another time, but I need to save money on the PSU. And they aren't too expesnsive for when I want to crossfire.

Thanks everyone, I'll get this PSU :)
 
of course you could crossfire with the 7970 it is a very very powerful card and can do 4 way crossfire but it will go above your psu's wattage (amperage on the 12v)
and you saying it's like in the top ten best radeon cards. IT IS THE SECOND BEST CARD THAT AMD MAKE (sorry for caps!)