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  1. #1
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    Dual EPS/CPU connector (2x 4+4) - When the second one is required? (APEX)

    Hi Folks,
    To the point: My PSU doesn't have a second EPS/CPU 8pin connector. I just connected one and everything works fine... i have a Rampage VI APEX with a 7900x + Strix GTX1080.

    I did a simple overclock to 4.4ghz and everything was stable and smooth as hell.

    So... When the second 8pin (CPU/EPS cable) is needed on the motherboard? I read about this as a requirement for "Serious overclocking". What's that? 5Ghz+?

    is there any REAL drawback in not using the second 8pin connector in the MOBO?

    Thanks!
    Last edited by BattleRaT; 09-27-2017 at 08:33 PM.

  2. #2
    ROG Guru: Blue Belt Array jab383 PC Specs
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    The REAL drawback is the low power rating of any PSU that has only one 8-pin motherboard cable. The R6A and the CPUs that run on it are power hogs with all their cores, whether overclocked a little, a lot, or not at all.

    I think that with a PSU capable of a 7900X and a GTX1080, at least 750 watts but others may disagree, just use the cables and sockets provided in the interest of efficiency.

  3. #3
    Tech Marketing Manager HQ Array Raja@ASUS's Avatar
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    Depending on the connector, a single eps 12 v 8-pin is rated for around 280W. If your cpu is pulling more than that, then you should plug in the additional connector. It isn't difficult to pull that type of power with these cpus, so you'd be best advised to invest in a good psu.

  4. #4
    ROG Guru: Black Belt Array Korth PC Specs
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    Quote Originally Posted by BattleRaT View Post
    I did a simple overclock to 4.4ghz and everything was stable and smooth as hell.
    Does the overclock remain stable under stress? Maybe some Prime95?
    Does it throttle more frequently under load (like, when you need it most in a heavy game)?

    I always use and recommend using all mobo power inputs, they were put there for a reason. Even if it looks like the mobo runs well without using them.

    Quote Originally Posted by jab383 View Post
    The REAL drawback is the low power rating of any PSU that has only one 8-pin motherboard cable. The R6A and the CPUs that run on it are power hogs with all their cores, whether overclocked a little, a lot, or not at all.
    Agreed. Low-rated and low-quality and low-priced PSUs are just not good enough for a costly "elite-tier" motherboard (with costly processor and memory, etc).

    Why go with a borderline and carefully calculated "proper-rated" PSU (with carefully calculated power factors and other corrections or margins), just go overkill with a blatantly over-rated PSU. Better stability, better reliability, better performance. Even runs a little cooler, a little quieter. It assures best possible longevity of the motherboard/etc, while a merely "adequate" PSU will often de-rate more rapidly over the years and contribute to permanent motherboard/processor/memory failures. Expensive hardware, it's worth spending a little extra to buy yourself some "insurance" where it's needed most. (It's worth spending even more buying a backup UPS unit, but sadly nobody listens these days, lol).

    Some of the extreme LN2 processor overclocks pull ~850W or ~1000W. Even chopping these values down to one-half (~500W) or one-third (~333W) for "normal" overclocks is instructive. Need to use those power pins. And need a robust PSU, otherwise what's left to power your GPU card(s) and everything else in the system when the CPU draws 500W?
    Last edited by Korth; 09-26-2017 at 09:51 PM.
    "All opinions are not equal. Some are a very great deal more robust, sophisticated and well supported in logic and argument than others." - Douglas Adams

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  5. #5
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    OK guys, message received! time to upgrade my PSU ;-)

    Now... just going more in deep and for the sake of having an interesting and detailed conversation: It looks one 4+4 CPU/EPS cable should be enough to provide about 270W to the CPU without having issues with the PSU, Cables or MOBO. I was checking a very good video at gamernexus channel and it looks the VRM should pull like 250W at 4.4ghz with Skylake-X, check here:

    https://youtu.be/_YzIuPJSLv4?t=8m24s

    So, despite the fact the proper way to go here is to connect all CPU cables the MOBO could have (2x 4+4pin)... Do we agree one should be "enough" for mild olverclock such as 4.4ghz for a 7900x ?
    Last edited by BattleRaT; 09-28-2017 at 02:47 PM.

  6. #6
    ROG Guru: Yellow Belt Array G75rog PC Specs
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    I have 3 requirements for a PSU.
    1: I do NOT hear it in operation.
    2: It has enough cables to populate ALL the power connections on a MB.
    3: An APEX MB with a liquid cooled 7900X, 64GB RAM, AMD Vega 64 Liquid GPU, full load of NVME SSD drives (no mechanicals allowed), additional PCIE cards, and USB devices will not be enough to cause it to run hot enough that I can hear it's fan running.

    My current PSU is a 1200w NZXT. I gladly pay a bit more for silence and lack of aggravation.
    Last edited by G75rog; 09-27-2017 at 11:12 PM.

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