Can an 12V 2x4-pin substitute for a 12V 8-pin?

[earwicker7]

The motherboard on the PC I'm building (1st time!) supports 2 8-pin connectors for powering the CPU. My power supply only came with one 8-pin connector, but it also has a connector that looks exactly the same, except it terminates into two 4-pins, so I'm guessing they are basically the same cable. Can I use that cable as a second 8-pin connector? Or do I need to buy a second cable?

 

[patonb]

Becareful...... You only need 1 pin, and itsd the 4x2 one. The other 8 pin is a pci-e connecter DO NOT USE THAT FOR THE CPU

What board do you have anyway?

 

[earwicker7]

No, it's not the PCI connector, I know what those ones are (kind of sort of; they have big labels on them so they're hard to miss lol)... this actually says, on both the power supply, the cable, and the motherboard, "CPU 8 pin". And there was a sticker on the motherboard (otherwise I wouldn't have noticed) which said "supports extra CPU 8 pin".

It's the Gigabit GA-X58A-UD9 R, and I'll be running an i7 980X, so it needs all the juice it can get The motherboard manual says that extreme editions need to run with the 8 pin for stability purposes.

EDIT--D'oh! I went in and looked more closely at the manual, and it does say to use a 2x4 for the cpu... so what was the 8 pin CPU cable that was connected to my power supply, and why is there an extra 8 pin connector on my motherboard?

 

[patonb]

Because folks usually runnning 1500W psus are running extreme systems... ie multi cpu servers. 2 cpus need 2 12V lines.

Seriously though, unless youre tri-sli you could have saved yourself abunch of cash and went with 1000Ws and still been safe.

 

[earwicker7]

That part makes total sense, so now I'm just wondering why there are two inputs on the motherboard.

Right now I'll only be running two 5970s, but I figured I should future-proof and just spend a little extra on the 1500W. You never know what you'll add down the road.

 

[Slaymate]

My E760 Classified mobo also has (2) 8-pin mobo power connectors. You only have to use (1) of the connectors, the 2nd connector is there for the extreme overclocker who may need the stability provided by the extra back-up power.

If you want to use both 8-pin mobo connectors you can use this adapter with (2) spare 4-pin molex connectors.
Logisys 12V Molex to 8pin P8 Adapter fro Motherboards Products Model: AD202 [AD202] : Performance-PCs.com, ... sleeve it and they will come

 

[earwicker7]

So what's the difference, electrically speaking, between the output jacks of a 2x4 and an 8? To me, it looks like all of the wires would end up routed to the same place. Am I missing something?

 

[patonb]

Well, some mobos only have a 4 pin, and not the 8 pin. So to accomidate they have a 2x4.

Theres nothing really different between the 2x4 or 1x8.

 

[earwicker7]

So I can go ahead and use one 2x4 and one 1x8 (both came with the power supply, so I wouldn't have to buy anything new) to fill up the two slots? I know it's probably overkill, but I've never known of a situation where more electrical headroom was a bad thing lol.

 

[patonb]

Have you read the thread about bthe usb cable???

J/K if you want both, go ahead... just one extra cable to hide.