PSU-Motherboard cables, which to use.

[Nakkiel]

PSU: Antec CP-1000 1000W
http://www.newegg.com/Product/Product.aspx?Item=N82E16817371036
Motherboard: MSI 890FXA-GD70
http://www.newegg.com/Product/Product.aspx?Item=N82E16813130274

The P1 is plugged in, but there isn't a cable labeled P2, which is the other I need to plug in. There is a P3 that is an 8-pin connector, which is the same size as what the P2 is supposed to be, and another just labeled CPU that is sort of a double cable with 4 pins each, so it would also fit there.

The P1 has something similar to the "CPU" double cable where it lets you only use 20 pins instead of 24 if you want to. So is the "CPU" actually P2, should I use P3, or neither?

 

[Nakkiel]

I've looked around and found 1 site that said the two 4-pin cables labeled CPU can be used in the 8-pin motherboard, but it did not say if it was better to use an 8-pin and if the "P3" is any different than that connector would be.

Can anyone tell me for sure which to use before I plug the thing in? Really nervous it might be the wrong one and do bad things to my motherboard.

Another detail that may be important is its ATX.

 

[hunter315]

P1 and P2 and P3 are just arbitrary labelings, there is no difference between the 4+4 pin connector and the 8 pin connector electrically, the 4+4 just adds support for boards that can only use a 4 pin connector and for boards that need 2 8-pin CPU power connectors.

The slots are keyed so you cannot put the wrong one into the wrong slot without a lot of work and mashing of plastic, if it fits in easily then its the right one, if it seems really hard to get into the slot dont force it, it may be a PCI-E connector instead(intentionally keyed different to prevent it)

 

[user 18]

It's uncommon for a PSU to have a 4+4 and an 8-pin connector. Use the 4+4, that's the safe bet. Looking at Newegg, it looks like the 4+4 is labelled CPU, and there are 2 6+2 pins, labelled PCI-Express 8-pin. The 4+4 is definitely the CPU connector.

 

[Nakkiel]

Best answer selected by Nakkiel.

 

[Nakkiel]

I finally found something on it buried in the documentation. The P3 is for some other type of power connection to a motherbord, althoough it still doesn't say if it could be used for it. The one labeled CPU it is though.. that connection is specifically for the CPU, so makes sense.

 

[hunter315]

It's uncommon for a PSU to have a 4+4 and an 8-pin connector. Use the 4+4, that's the safe bet. Looking at Newegg, it looks like the 4+4 is labelled CPU, and there are 2 6+2 pins, labelled PCI-Express 8-pin. The 4+4 is definitely the CPU connector.

Its not uncommon on higher end boards, dual socket boards tend to have 2 8 pin connectors for both CPUs, some higher end single socket boards built for extreme OCing have two connectors for additional power for the CPU if needed.

The 8 pin connector was likely listed in the documentation as an EPS 12V connector, EPS is a server standard and was migrated over to standard consumer PCs as CPUs started needing more than the 75W that a 4 pin ATX 12V connector could handle, some board and power supplies treat EPS 12V and ATX 12V as interchangable, but any 8 pin CPU power socket is EPS 12V, a 4 pin socket is ATX 12V. You will notice that the 4+4 pin connector and the 8 pin connector have the same pinout.

 

[Nakkiel]

The 8 pin connector was likely listed in the documentation as an EPS 12V connector

Yup, although I think it was on an online documentation I found that out, still have yet to see it anywhere in the packaging. I do wish it was a modular cable though, hate thats its just there not plugged into anything.