Is this PSU enough to overclock the i5 6600k and the R9 390? I'm hoping to get around 4.5 ghz
Sure, assuming you aren't trying to run like 50 hard drives on the side or something.
Or some Delta fans.
alright cool. I was worried because in the specs of the sapphire r9 390 it required a 750W psu
Another reason the GPU manufacturers suggest the power supplies the way that they do is because power supplies of certain wattage ranges tend to have certain types of PCI power connectors. They suggest 750w for the 390 because any worthwhile 750w supply will have the minimum number of PCI 6+2 connectors to power their card. (In addition to what 526christian said)
Graphics card manufacturers go a bit high in requirements because they don't know the rest of your hardware, your uses, etc.
well then thanks alot sir!
You can dip under the recommended wattage a bit if your PSU is well-built.
is this psu well-built then?
Probably, assuming the rest of the components don't eat too much power