Hi, 
 
   My motherboard requires a 4-pin EATX 12v Connector as well as an 8-pin EATX 12v Connection, but the CPU cables included only have 4+4 pin CPU cables and the connector pieces won't match up properly if I just put them together.  The 650w comes with an 8-pin CPU cable and a 4+4 pin adapter so I'm assuming they aren't interchangeable?? I've read people suggesting that the connectors will go in even though they don't match but since some are grounds and others 12v, it doesn't seem like it would work. 

The EPS (CPU) +12V 4+4 pin connector complies with industry-standard specifications and has to fit (unless they're deformed, which is highly unlikely) in the motherboard's CPU power sockets.
 
There's a left and a right part of the connector..They may also have a little tab/notch at the top where one 4-pin part has to fit in first, slightly ahead of the other 4-pin part, like a 6+2 pin PCIe power connector does.