Dedicated single +12V rail

  • gamingdave 14 Nov 2013 11:17:02 4,725 posts
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    My corsair PSU recently died, a TX750. They are going to replace it under warranty (it was 4 years old) but have said the TX750 is now an obsolete/discontinued product despite still being listed on their site. They have offered a RM750 as a replacement.

    On nearly all accounts the RM series seem better. Its fully modular, more efficient being gold rated (as opposed to the TX bronze), and super quiet. It does only have one 1 EPS Connector, but I fail to see why I would need 2, and has one less molex, but I would only be using those for case fans anyway.

    The one key difference, at least touted by corsair, is the TX has a dedicated single +12V rail. And my question is what difference does that make?

    The rest of my system is an Asus P7P55D PRO MB, i5-750 (overclocked to 4.2Ghz) and a 5850. The 5850 is going to be replaced with something like a R9 280X and I have contemplated a new MB and CPU too. Then it's just a BR drive, an HD and soon to add SSD.

    Is the dedicated rail required for the CPU overclock? Will not having a dedicated rail cause an issue if further down the line I want to go SLI/crossfire?

    Had a read around and it seems with a decent PSU it shouldn't make a difference, but would appreciate the input from the more knowledgeable here before I either accept the replacement or insist on a TX line unit.
  • pauleyc 14 Nov 2013 13:06:36 4,548 posts
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    I can't help you with the dedicated 12V rail (it's probably not that important) but the RM750 might not be such a good replacement after all if HardOCP's review is to be believed.
  • TheBlackDog 14 Nov 2013 23:25:46 1,061 posts
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    @gamingdave Single vs multi rail is nothing to worry about - performance and efficiency wouldn't be affected by the number of rails although there are plenty of people arguing that each is better than the other (the only valid case seems to be multi rail is slightly safer if the over current protection screws up because there would be less amps on the faulty rail to fry your components as the amps are shared across more than one rail).

    I just bought a PSU last week and found this site useful: Eggxpert Tiered Power Supply List . They list the RM550 as decent but don't list the other wattages in this RM series. Often this is deliberate as sometimes the build quality, components, etc can be different within the same series of PSU's.

    I found this thread on Toms where it is claimed that the 750w PSU's in the RM series are made by a different OEM and are therefore slightly "lower-grade" (neither are made by Seagate who are rated and who made the TX750 v2 that you are replacing). Might be BS but might also explain the ommission on this Tiered PSU list.

    The HardOCP review was tough on the PSU to give it a fail but I found positive reviews from Hexus and Hardware Heaven. Tech Power-up gave it a positive review but with plenty of caveats, like using caps made by a manufacturer with a bad reputation and a few other issues.

    Personally, I'd want the TX model. If you can't get the TX version, which is arguably a higher quality product, I'd ask for my money back, or at least a refund of what it cost to ship it to them for RMA - then I'd put that towards a PSU that gets overwhelming positive reviews from multiple sources (there are plenty to choose from on the tiered PSU list and other PSU lists).
  • mal 15 Nov 2013 00:01:57 29,326 posts
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    I'd have thought the main reason for using dedicate power circuitry is to eliminate any noise due to variable load one one rail affecting the other. I doubt that's an issue in any sane PC setup unless you've packed it to the gills with hard discs or got too many graphics cards in there or something. In which case, keeping the thing from quietly cooking itself is probably more of an issue than wobbly feeds.
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