EPS12V question

I just bought a new mainboard with the EPS12V connector (8 pin 12v power for CPU) - the manaul that came with the board says I need to connect an 8-pin power connector here or the system won't start.

I also bought a new power supply, it came with 4-pin 12v and 6-pin 12v connectors, but no 8-pin connectors.

There is enough room around the connector to connect both, and they will go on (but the clip on the 4-pin one has nothing to lock onto). Can this be done (safely)?

Also, what are the pin/power assignments? From what i have seen, it seems to be that the four pins on the side of the clip are +12v and the other 4 pins are ground...is this correct?