8 pin cpu connector query

[Mithrandir]

I've been putting together the parts to my C2D rig, but I'm bit of a noob when it comes to 8 pin as I've never had to use it.
I'm using a Xigmatek modular PSU (NRP-MC651) and trying to connect the 8pin CPU cable.
However, I noticed the plugs have different ends. I've attached a photo but not sure if it's clear enough.

Basically, the top plug in the pic seems to be able to split into 2 (think its a 4+4 pin) and only 2 of the pins are square whereas the remaining 6 are squres with 2 corners cut.

The other end of the cable (bottom of pic) is one plug (cannot split) and is 4 squares and 4 non-square pins.

Originally, I plugged in the splitable end into the psu but wouldn't go in (this was when I noticed the ends are different)
I switched this over and this plugged into the motherboard although the motherboard has 4 square pins and 4 non squares and this fits and the other end fit into the psu.

The colours seem to match with yellow on one row and black on the other.

In addition, there is also a 4 pin connector pre-attached to the psu.

Do I have a dodgy modular cable or am I meant to split the 8 pin and use one half along with the captive 4 pin?

Many thanks

[PeterStoba]

If there is an 8pin cable and an 8 pin slot on the motherboard you use it to give it more power for overclocking iirc, although you can use just a 4pin if you need to.

If it fits and the splittable end is at the motherboard i see no problem

[mac124]

Is the pre attached 4 pin connector part of the main motherboard power cable / connecter? If so then that connects into the main power connector on the motherboard. If not then i suspect thats the one to use instead of the modular 8 way cable you mentioned if your motherboard only has a 4 way atx power connector.

As Peter said the split end, 2 4way connectors, goes to the 8way connector on the mobo, the non split end goes into the psu.

[Mithrandir]

Thanks guys.
The 4 pin is attached to the PSU along with the 24 pin atx connector.
The motherboard is a Biostar TP45-HP and has an 8 pin cpu connector but I suppose I could use the 4 pin rather than the modular 8 pin. However, I'd like to overclock the cpu so not sure how this will affect it.

Im worried that the (wrong) 8 pin might take out my system.

[strike-down]

Those by the looks of it ARE NOT the 8 pin connectors you're after, from the image they look like 8 pin (6+2 pin) PCIE connectors

[Saracen]

Those by the looks of it ARE NOT the 8 pin connectors you're after, from the image they look like 8 pin (6+2 pin) PCIE connectors

Good point.

Mithrandir, that PSU has two type of 8-pin connectors and cables, one for CPU power and for for graphics (PCI-E) cars. They are NOT interchangeable.

According to the manual, one has five yellow (12v) lines, on pins 1 to 3, and three black (ground) wires (on pins 4 to 8). That is the PCI-E connector. Do NOT connect it to the mobo CPU slot (though you shouldn't be able to without using considerable force).

The other has four yellow (12v) lines on pins 5 to 8, and four black (ground) on pins 1 to 4. That's the CPU connector for the mobo.

If you look, you can see that though the colours are the same, one plug supplies 12v on most pins where the other is ground.

[Mithrandir]

Those by the looks of it ARE NOT the 8 pin connectors you're after, from the image they look like 8 pin (6+2 pin) PCIE connectors

The 8pin PCIe plugs are attached to the psu along with the 24 pin ATX and 4 pin CPU.
The modular PCIe cables are 6pins only and the only modular 8pin cpu cable is as pictured. Not sure if the cable is incorrectly made, or an EPS 12v cable or the cable is correct but the 4 non-squared pins should be 2 squared and s non-sqaured.

[strike-down]

Edit: Ignore me, misread it
http://www.xigmatek.com/download/NRP-MCusermanual.pdf

[Mithrandir]

Good point.

Mithrandir, that PSU has two type of 8-pin connectors and cables, one for CPU power and for for graphics (PCI-E) cars. They are NOT interchangeable.

According to the manual, one has five yellow (12v) lines, on pins 1 to 3, and three black (ground) wires (on pins 4 to 8). That is the PCI-E connector. Do NOT connect it to the mobo CPU slot (though you shouldn't be able to without using considerable force).

The other has four yellow (12v) lines on pins 5 to 8, and four black (ground) on pins 1 to 4. That's the CPU connector for the mobo.

If you look, you can see that though the colours are the same, one plug supplies 12v on most pins where the other is ground.

The modular 8 pin is definitely 4x yellow and 4x black.
I think I might use the 4pin cpu cable for now and query the cable with Xigmatek.

[mac124]

Of the two connectors pictured the top one is clearly split as a 4+4 this is the end that MUST be plugged into the motherboard if the motherboard has an 8 way connector. I suspect you use half of this is the motherboard only has a 4 way connector.

The only thing that confuses me is the seperate 4way connected directly to the psu, i suspect this goes with the main motherboard connector to make a 20+4 but please check.

[strike-down]

No, the manual says that it has a 24pin ATX as standard. Just look at that manual i linked you to mate, it tells you the difference between them all

[Agent]

AFAIK - the wrong ones shouldn't physically fit as the plastic slots are keyed different.

[LuckyNV]

AFAIK - the wrong ones shouldn't physically fit as the plastic slots are keyed different.

indeed this is correct unless you fit your cables with a mallet

[Mithrandir]

Of the two connectors pictured the top one is clearly split as a 4+4 this is the end that MUST be plugged into the motherboard if the motherboard has an 8 way connector. I suspect you use half of this is the motherboard only has a 4 way connector.

The only thing that confuses me is the seperate 4way connected directly to the psu, i suspect this goes with the main motherboard connector to make a 20+4 but please check.

The 4 pin is not the +4 on the 24pin as I've plugged that into the mobo already.

AFAIK - the wrong ones shouldn't physically fit as the plastic slots are keyed different.

That is what I thought, but since the 4+4 has a pin configuration I've not seen before (see below) I think the plug is wrongly molded. Funnily enough the plug goes into the mobo fine.



to fit into this:

[mac124]

In that case you have 3 choices, use it after but only after triple checking it is wired correctly first (i'd use the paperclip method to power the psu up and physically measure which pins actually have 12v on them and compare that to the info in the mobo manual regarding the pin out of the 8way connector).

Or contact the psu manufacturer and send them pictures of the 4+4 end of that cable and the connector on the mobo stating your concerns about using it and see what they say.

Or just use the 4way connector in half of the 8way socket. It should only fit in one end of it.

If you don't know how to switch a psu on with the paperclip trick here's a linky showing how.

http://aphnetworks.com/tutorials/psu_paperclip_trick

[Saracen]

What you have there is one of two types of 4+4. That in itself is a bit weird, since the manual says that PSU didn't shipped with a 4+4. Oh well, things change and documentation often doesn't.

The first type of 4+4 is moulded exactly the same way as an 8-pin, but in two half. Connections are identical, and if you glued it together, you'd have an 8-pin.

But there's a second type.

For this second type, the LEFT half 4 the 4+4 is exactly the same as the left side of a standard 8-pin. So you can plug in into the left side of the mob CPU connector.

The right side, however, is moulded differently. However, since rounded pins will fit in square holes, it will still fit the left side of the mobo CPU connector. If you look at the wiring, you'll also find that the two halves of the 4+4 are electrically identical, even if the mouldings are different on some cables.

Don't ask me why they make this second type. I presume there's some reason, but I've no idea what it is (some types of dual-CPU 4-pin boards, maybe).

So (in my opinion, but check it out for yourself, because if you plug it in and it fries something, I'm not buying you a new one ) )what you have is one of the two types of 4+4 CPU connector. Electrically, you should be able to plug either half into the left half of the 8-pin connector, but seeing as it's designed for it, common sense says to use the left half. And it should work.

My one concern is that the reason for splitting the power supply to the processor into two halves is because with power-hungry CPUs, it can draw a lot of power and if the connection is at all dodgy or dirty, resistance goes up and with it, heat generation. Obviously, if you draw a lot of power, than can be an issue.

You didn't say (that I noticed) what CPU you're using, but given that you said C2D I wouldn't have thought that would be an issue. It might with some of the more muscular (and older) quads. Clearly, motherboards are designed to take a range of processors, and supply power accordingly. You can get 4-pin to 8-pin adapters, but since that really just moves the potential source of heat from the mobo connector to the 4-pin to 8-pin-adapter joint, I'm not sure it'll help much if there's a problem, though it might prevent the mobo connector melting I guess.

In any event, it looks fine to me, but please, check it for yourself. Don't take my word for it.