They simply put more pins to better feed the on-board power supply (mostly for overclocking) ,the 4 pins that you have should be enough as long as the power supply is a good and quality one and as long as the other power connector is a 20+4.
If you observe abnormalities like instability or strange behaviors then maybe you should change the PSU or buy an adapter ,but generically speaking you should be ok..
Are you using the top performance APU ?!
The APU has build in graphics ,additional PCI-E cards are fed via 20+4 and via their own power connectors.
