z3n0mal4 Posted December 5, 2015 Share Posted December 5, 2015 Hello, I just ordered a RM750i as a replacement for my current TX850. Not that the old one doesn't do it's job, but because i needed a modular psu (and it looks better in my shiny new Obsidian 750D ^^). Heading for the online manual from the site i discovered i have the option to go single-rail as opposed to the multi-rail default. And i'm not that advanced in psu matters to know what would suit my configuration better. Any tips you can give me? Thanks Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted December 11, 2015 Corsair Employee Share Posted December 11, 2015 Just leave it as is. I doubt you'll have any issues. Link to comment Share on other sites More sharing options...
z3n0mal4 Posted December 15, 2015 Author Share Posted December 15, 2015 I agree :) Didn't change a thing. It's easier when i'm not given options. Link to comment Share on other sites More sharing options...
leftshark86 Posted December 16, 2015 Share Posted December 16, 2015 It's most likely better to leave it at the default settings. Here's a site I found helpful in explaining single vs multi rail options: http://www.overclock.net/t/761202/single-rail-vs-multi-rail-explained Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted December 16, 2015 Corsair Employee Share Posted December 16, 2015 Might as well go straight to the source: http://www.jonnyguru.com/forums/showthread.php?t=3990 ;): Link to comment Share on other sites More sharing options...
Vegan Posted December 22, 2015 Share Posted December 22, 2015 I like the single rail mainly as it is agnostic to the way the PSU is used. Try running 12 SSD or 16 hard disks, no PCI Express need apply. So the power can go elsewhere. Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted December 22, 2015 Corsair Employee Share Posted December 22, 2015 Well.. SSD's only use +5V. So how the +12V is set doesn't apply. Platter drives +12V load is only really high during initial spin up of all the drives if you don't have a means to stagger the spin up. Link to comment Share on other sites More sharing options...
alephnull Posted December 21, 2016 Share Posted December 21, 2016 Just leave it as is. I doubt you'll have any issues. What's the default? Link to comment Share on other sites More sharing options...
Riptide_NVN Posted May 17, 2018 Share Posted May 17, 2018 It definitely CAN make a difference. I have a RX Vega 64 in my system. With link set to multi rail (850hxi) the system would flat power off when I loaded Far Cry 5 levels. Battlefront 2 made it 5-10 minutes. Same thing. Set to single rail and the situation cleared up immediately. Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted May 17, 2018 Corsair Employee Share Posted May 17, 2018 It definitely CAN make a difference. I have a RX Vega 64 in my system. With link set to multi rail (850hxi) the system would flat power off when I loaded Far Cry 5 levels. Battlefront 2 made it 5-10 minutes. Same thing. Set to single rail and the situation cleared up immediately. Vega 64 wasn't around two and a half years ago when this thread was original made and I responded to it. Yes. Vega 64 is a power hog. You're using two PCIe connectors on one cable, aren't you? Not using two PCIe cables? Link to comment Share on other sites More sharing options...
Riptide_NVN Posted May 18, 2018 Share Posted May 18, 2018 Good guess and yes using one cable right now. I may install a second cable though at this point now that I've got it working it is questionable how much it matters. Link to comment Share on other sites More sharing options...
Corsair Employee jonnyguru Posted May 18, 2018 Corsair Employee Share Posted May 18, 2018 Good guess and yes using one cable right now. I may install a second cable though at this point now that I've got it working it is questionable how much it matters. As long as you don't experience a short on one of the +12V rails, single +12V rail is fine. But you can use two cables, switch to multiple +12V rail and it'll work flawlessly. Link to comment Share on other sites More sharing options...
npzeyer Posted June 25, 2019 Share Posted June 25, 2019 Sorry to revive this, but I'm so glad I found this thread. I too had the same problem. HX850i and dual RX Vega 64. Switched to single rail and problem solved. I found also others having the same issue even with Nvidia cards: As long as you don't experience a short on one of the +12V rails, single +12V rail is fine. But you can use two cables, switch to multiple +12V rail and it'll work flawlessly. Does this imply each pcie psu connector is own its own separate rail? Unfortunately with psu shroud on, I can't route an extra pair of pcie cables through the back of the case anymore since it's cramped enough I have to force the back cover back on as it is. In multi-rail configuration, it would be nice if the corsair link software could show power/current on each rail. Also given the current situation wouldn't it be better if the default was single rail or at least include a warning in the manual or separate warning sheet in the box? People using it with other OS's are kinda screwed too. Link to comment Share on other sites More sharing options...
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