PSU/Motherboard/CPU question

[kodiecorn]

So I have everything plugged in from my PSU to my mobo accept for a 8 pin cable or a 2x4 pin cable. Would me not having one of those plugged in make my PC not start.

I can switch from the 8 pin or 2x4 pin cable into the JPWR2 slot on my MOBO and would it matter which one I use.

 

Would just like to know because I'm returning my mobo and hope that's the problem and not the CPU.( yes I check if the PSU works )

 

Here are the specs if anyone wants to know 

msi z97 gaming 5 

i7 4970k

HyperX FURY 2 x 8 1866 DDR3

Rosewill Hive-750

[SonoDanshi]

Something like this happened to a friend of mine recently. He was upgrading his g/f pc and used the 8-pin connector for GPUs instead of the 2x4-pin EPS. This meant that the PC wouldn't power up at all. Once he switched to using the correct cable, it powered up immediately.

 

So yes it definitely matters what cables you use.

[kodiecorn]

4 minutes ago, SonoDanshi said:

Something like this happened to a friend of mine recently. He was upgrading his g/f pc and used the 8-pin connector for GPUs instead of the 2x4-pin EPS. This meant that the PC wouldn't power up at all. Once he switched to using the correct cable, it powered up immediately.

 

So yes it definitely matters what cables you use.

The 8 pins connectors I'm talking about plug into the motherboard not the GPU. I have PCI-E cables that plug into the back of my PSU for my GPU.

I switched from both 8 pin and 2x4 pin in the JPWR2 slot and the MOBO still didn't turn on.

[kodiecorn]

Also I think both of those cables from the back of the PSU the 8 pin and 4x2 pin wouldn't even plug into the GPU even if i tried, the alignments don't match up.