Question about Corsair Rm750x PSU Cables/Compatibility

Bappy on 29/01/2021 - 17:22
Last edited 29/01/2021 - 17:22

Hi All,
So I bought a Corsair RM750x from Facebook pretty cheap, and so far it seems to be working fine with my brief testing.

However the catch was it didn't come with full set of modular cables, specially I only have 1 GPU cable (one cable which has 2x 8PIN PCIE cables). The Seller has provided another similar PCIE cable from a Gigabyte PSU which looks like compatible however I read that it is very risky to use one brand's cables in another branded PSU…

Question1: Can I still use this one PCIE Cable with 2x 8PIN (2+6 PIN) PCIE Cables to power a RTX 3070 that requires 2x 8PIN PCIE cables? I heard it depends on single rail capacity of the PSU and as per my research RM750x has decent single rail capacity.

Question2: Where can I find decent yet cheap compatible cables for RM750x?
I already checked eBay and price seems very expensive (full cable set costs around $100, and one PCIE type 4 cable cost around $30). Aliexpress has them and price is also cheap however they are obviously not genuine Corsair cables, so not sure how safe it would be…

Thanks in advance.

Computing

Comments

  • Trance N Dance on 29/01/2021 - 17:30
    +2

    Q1:
    Can you? Yes.
    Should you? No.
    The 8pin spec is 150W for the cable, as long as the 3070 doesn't draw more than 225W you're fine (150W from the 8pin and 75W from the PCIe slot). If it draws more than that then technically you're operating out of spec.

    Q2:
    No, you should not use the cable from the Gigabyte PSU unless you're absolutely sure the pin out is the same.

    • Bappy on 29/01/2021 - 17:57

      Thanks heaps, much appreciated.

      Now I need to find a replacement Corsair Type4 PCIE Cable - they are so expensive

      Edit:

      Question: So what you saying both PCIE cables (from the same mother cable, i.e. one cable has a branch, means 2x 8PIN PCIE cables) only supplies 150W total power? I thought it would be 300W total

      • Twix on 29/01/2021 - 18:05
        +1

        Mwave and PC Case Gear sell Corsair Type4 PCI-E cables.

      • Trance N Dance on 30/01/2021 - 04:36
        +1

        No, each 8 pin PCIe cable under the ATX spec supoplies 150W. So if there's only one cable coming out from the PSU then under the ATX specification it should only handle 150W without causing problems.
        I assume you mean cables like these where there's two plugs on one end but still one cable.
        https://images-na.ssl-images-amazon.com/images/I/51TN7U9mQjL.AC_SX466.jpg
        If so then yes under ATX spec both those plugs will provide a combined power of 150W.

  • impoze on 29/01/2021 - 18:34
    +2

    Yep, don’t risk using another cable that fits as the pin configuration may be different

    See this recent story that cost the user 4x drives - https://www.reddit.com/r/unRAID/comments/l4rbp6/psa_modular_…

  • Graduate on 29/01/2021 - 22:54
    +1

    Yeah, our RMx' have "In-cable capacitors", a negative itself, and likely contra to finding right, compatible and safe, extra or replacement cables.

    To secure enough Molex (no more than 4 HDDs per cable to be electrically sound) for my legacy rig, I researched every darn PSU available (made a list of 150+ links) and my best option was just to buy two RM850x (White were $209 each last November @ Amazon AU - Black is currently cheaper and is a revised Version 2 model, fwiw). And so, I've got 6 PCIe (shall be 4 to spare) cables in my hands, and if you, OP, were in front of me, I might be compelled to set two down and look the other way… (but neither such a meet will take place to make the drop, nor willing to post - sorry, Bappy!)

    Buy cheapest second[hand] RMx PSU for the modular cables was my initial thinking, but having a second good wattage PSU (and matching cables, right) as backup is saner than paying for Corsair's premium cable package - that is despite hearing that the official kit may be thicker gauge cables, better quality than what's bundled with the PSU.

    https://i.redd.it/qfwh3kboeyl51.png

    • Bappy on 30/01/2021 - 00:23

      Thanks for the information, appreciated

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