supernova 650 G3; i have a MSI motherboard.[x450 Gaming Plus Max] AMD socket  am4... the 650 gold manual say's; for overclocking, i need a EPS/ATX12V4(4+4)-Pin. there is a place on the Motherboard for a 4 prong plug. even if, i had that cord. i wouldnt now how to plug it into the motherboard, or where to plug it into the power supply. maybe it needs a special type plug?
this is a workstation setup, and i might need the extra power to the board at a later date. Rendering.

The solid 8-pin part of the cable labeled "CPU" plugs into the PSU..Then on the other end, the 4+4pin connectors fit together a certain way (look closely at the connectors) and plug into the motherboard CPU_PWR1 socket.

There's another 4-pin CPU_PWR2 socket on that motherboard, right?..If so, that's for extra power to the CPU for overclocking/stability and the SuperNOVA 650 G3 does not have a cable/connector for that one..You'll have to use adapter cables like are in the links below if you want/need to do that, or get a PSU that has the neccessary cables/connectors, but just using the one 8-pin (4+4) connector should be fine, see how it works.

In case you're wondering, yes, an 8-pin CPU power connector will fit in a 4-pin motherboard socket, 1/2 of it will hang outside the socket if nothing is in the way.
 
There are all kinds of adapters/splitter cables out there if you want/need to use them.
 
EPS12V 8-pin Y-splitter Power Cable here.
P4 4-pin to Molex Cable Adapter here.
SATA to ATX P4 Adapter here.