'cpu' vs 'pcie' cable; same same?

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yd

yd

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  • #1
    Before I go and blow shit up, I figure I will confirm here.

    I have to get a power cable to my msi 1080 gpu. Now, in my previous build I would swear I only had a 2x3 style connector going to a 4x4 'slot' on the card.

    So new build, I have two cables that are 2x4 on each end. One is a 'cpu' cable (I have 2 in the modular cable bag, one is already going to the mobo) - they are all 'together' on each end and one end is a small clip so that has to go to the power supply side, the other could go to the gpu.

    The other is a 2x4 connector on one end and a 3x2 with a break away 1x2 connector on the other end (that end labeled pcie).

    Now I am certain I could plug the pcie cable (with 3x2 and 1x2) into the gpu and orientation is forced by the clip so couldn't screw it up. But that cable also has an extension on it of another 3x2/1x2 I assume because some gpu's can use a pair of these things.

    However, I would prefer to use the cpu cable if it is wired the same as it won't look like ass with that other end out dangling in space.

    I went to this spot at Corsair to see what it says for my hx1200 platinum power supply and it talks about type 3 and 4 cables but doesn't really tell me which is which. It does mention/disclaim that all other cables (sata/pcie etc are the same.

    https://www.corsair.com/us/en/psu-cable-compatibility

    So, could I run the cpu cable to that gpu? Including a photo for thoroughness. cpu is all in one block, pci is split out as you can see and there is an extension running below and down in the photo the second one.

    avPlK8O.jpg
    J

    JessF

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  • #2
    No!

    They have different pin-outs. A quick search gave me this site:
    https://www.moddiy.com/pages/Power-Supply-Connectors-and-Pinouts.html Where there is descriptions and pictures.

    Compare "8 Pin EPS +12 Volt Power Cable Connector" (or "4+4 Pin +12 Volt Power Cable Connector") to "8 Pin PCI Express (PCIe) Power Cable Connector":

    CPU/Mobo has: GND on pin 1-4 and 12V on pin 5-8, so one side is all power and one side is all ground.
    PCI-E has: 12V on pin 1-3 and GND on pin 4-8, so one side is all ground, but the other is mixed.
    yd

    yd

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  • #3
    Sonofa.....well, I ain't got a chance at a beauty award in the 'post yer pic of yer rig' thread now.

    Why cant 2x4 etc be uniform, standards, you know, make things easy.

    edit - well I have a bendy hide a cable behind a cable solution along with some creative snaking. So pci-e it is then.

    Now for a bunch of final checks pre power/ignition/liftoff - hopefully liftoff, not just ignition!
    M

    mpat

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  • #4
    yd said:
    Sonofa.....well, I ain't got a chance at a beauty award in the 'post yer pic of yer rig' thread now.

    Why cant 2x4 etc be uniform, standards, you know, make things easy.
    Click to expand...

    Wait until you decide to rebuild a computer with a modular PSU and realize that a) you really really can’t reuse modular cables from another PSU that you happen to have lying around because there are absolutely no standards there, and b) there is nothing in the pinning to prevent you from trying to do so. You will notice your mistake when you turn it on and you smell the magic smoke coming out.

    (No, I have not made that mistake, but I have heard of too many others who have.)
    yd

    yd

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  • #5
    mpat said:
    yd said:
    Sonofa.....well, I ain't got a chance at a beauty award in the 'post yer pic of yer rig' thread now.

    Why cant 2x4 etc be uniform, standards, you know, make things easy.
    Click to expand...

    Wait until you decide to rebuild a computer with a modular PSU and realize that a) you really really can’t reuse modular cables from another PSU that you happen to have lying around because there are absolutely no standards there, and b) there is nothing in the pinning to prevent you from trying to do so. You will notice your mistake when you turn it on and you smell the magic smoke coming out.

    (No, I have not made that mistake, but I have heard of too many others who have.)
    Click to expand...

    I almost got to learn that one. I think I may have actually gotten lucky previously with a 'this cable is the same and looks nicer'. I was keeping around modular cables as 'spares'...they are going to the bin now.
    Dystopia

    Dystopia

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  • #7
    mpat said:
    yd said:
    Sonofa.....well, I ain't got a chance at a beauty award in the 'post yer pic of yer rig' thread now.

    Why cant 2x4 etc be uniform, standards, you know, make things easy.
    Click to expand...

    Wait until you decide to rebuild a computer with a modular PSU and realize that a) you really really can’t reuse modular cables from another PSU that you happen to have lying around because there are absolutely no standards there, and b) there is nothing in the pinning to prevent you from trying to do so. You will notice your mistake when you turn it on and you smell the magic smoke coming out.

    (No, I have not made that mistake, but I have heard of too many others who have.)
    Click to expand...

    The solution to this is to pick a PSU vendor and stick with them for all your PSUs.
    M

    mpat

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  • #11
    I have actually stuck with Seasonic for my PSUs, partly because I thought it was safer, but I don't like to be restricted like that. For my current build, I really really wanted a PSU that followed the ATX standard - meaning length of 140mm. Most high power PSUs are longer than that now. I found one in the Seasonic Focus GX series, which was nice for me because I had Seasonic models before, but that was just luck. If that option had been available exclusively in some other brand, would have been forced to switch - and potentially burn up the new build.
    M

    mpat

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  • #13
    continuum said:
    Most high power PSUs are longer than that now.
    Click to expand...
    Most have been that way for a long time. :/ (depending on your definition of a "high power PSU" and how that may have changed over time, too!)
    Click to expand...

    Probably true. I was pleasantly surprised that I could get a 650W PSU from a reputable brand at 140mm.
    Doomlord_uk

    Doomlord_uk

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  • #14
    JessF said:
    No!

    They have different pin-outs. A quick search gave me this site:
    https://www.moddiy.com/pages/Power-Supply-Connectors-and-Pinouts.html Where there is descriptions and pictures.

    Compare "8 Pin EPS +12 Volt Power Cable Connector" (or "4+4 Pin +12 Volt Power Cable Connector") to "8 Pin PCI Express (PCIe) Power Cable Connector":

    CPU/Mobo has: GND on pin 1-4 and 12V on pin 5-8, so one side is all power and one side is all ground.
    PCI-E has: 12V on pin 1-3 and GND on pin 4-8, so one side is all ground, but the other is mixed.
    Click to expand...
    Er, don't you mean the PSUs themselves have different pin-outs? Meaning you can't connect the mobo 8pin cable to the PCI-e socket? and vice versa? Or are you saying that the way the cables themselves are wired on one end is different/asymmetric to the other end of the cable???

    If I had half a clue where my DMM was I'd go check this myself now, coz I can't believe the cables are actually manufactured differently like that.

    Also, what about the keying on the plugs and sockets? Is that different? The 6pin PCI-e plus is keyed differently, so couldn't go into an 8pin socket?
    J

    JessF

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  • #16
    Doomlord_uk said:
    JessF said:
    No!

    They have different pin-outs. A quick search gave me this site:
    https://www.moddiy.com/pages/Power-Supply-Connectors-and-Pinouts.html Where there is descriptions and pictures.

    Compare "8 Pin EPS +12 Volt Power Cable Connector" (or "4+4 Pin +12 Volt Power Cable Connector") to "8 Pin PCI Express (PCIe) Power Cable Connector":

    CPU/Mobo has: GND on pin 1-4 and 12V on pin 5-8, so one side is all power and one side is all ground.
    PCI-E has: 12V on pin 1-3 and GND on pin 4-8, so one side is all ground, but the other is mixed.
    Click to expand...
    Er, don't you mean the PSUs themselves have different pin-outs? Meaning you can't connect the mobo 8pin cable to the PCI-e socket? and vice versa? Or are you saying that the way the cables themselves are wired on one end is different/asymmetric to the other end of the cable???

    If I had half a clue where my DMM was I'd go check this myself now, coz I can't believe the cables are actually manufactured differently like that.

    Also, what about the keying on the plugs and sockets? Is that different? The 6pin PCI-e plus is keyed differently, so couldn't go into an 8pin socket?
    Click to expand...

    I meant the connectors on the motherboard and graphics cards have different pin-outs. Thus the connectors on the ends of the PSU cables that connect to the motherboard and graphics cards have different pin-outs.

    If you have a modular PSU so the cables detach at the PSU end, the actual connectors at the PSU end do vary between manufacturers and product lines as others have mentioned.

    As the motherboard and graphics card have different number of power and ground pins, the pin-outs on the connector at the PSU end would likely also be different. You could make a "universal" connector at the PSU with enough pins to support both and have different cables where the connectors only use the relevant pins. If you don't have "universal" connectors at the PSU, but connectors dedicated to each type, you could have "universal" cables that simply connect pins 1-to-1, but that would also need to support the keying for both at the other end.

    The connectors are also keyed differently (at least at the MOBO/GPU end), so in theory you can't use the wrong one (sometimes you can with a little force).
    malor

    malor

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  • #17
    As a belated reply, if you think about it, why would they bother stamping PCIe and CPU on the cables if they were the same? They are definitely not, and generally won't fit into each other's plugs, because different pins will be round versus square.

    As far as modular power supply cables go, as a general rule, use only the specific cables you got with a specific supply. Never mix cables unless they're the exact same model number bought at the exact same time, and maybe not even then. If you lose cables, and need extras, order directly from the manufacturer, with them explicitly telling you that the cables are right. If you can't do that, replace the PSU.

    If you really know what you're doing, you could probably build custom cables, but unless the supply was very expensive, it's not likely worth the time and/or the risk.

    Custom aftermarket cables often work, but even those can be risky because OEMs sometimes change designs without changing model numbers. It's generally best to order those with the PSU when it's bought new, rather than trying to find them later.
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