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-   -   Rm850x vs Rm850i (https://forum.corsair.com/forums/showthread.php?t=188863)

RodrigoDRT 07-18-2019 08:42 AM

Rm850x vs Rm850i
 
Just to be sure, afaik, the only difference is that the i one has the icue/c-link? monitoring thing? but is it really just for monitoring? any adjustements?

thats it about them? cause if so, i found them for the same price, and by logic the i one would be better if everything else is the very same, for obvious reasons.

corsican 07-19-2019 04:01 AM

nope the fan on the RMi series is a true FDB (fluid dynamic bearing) fan and the one on the RMx series is only rifle-bearing fan (shorter lifespan which is why it's set to 0db mode to preserve life cause you can't afford to have a rifle-bearing fan spinning all the time)

Krokarn 07-19-2019 06:23 AM

RMi series can be switched between Single och Multi Rail OCP, that can not be done on the RMx series.

RodrigoDRT 07-19-2019 07:30 AM

what exactly does single/multi rail ocp does? ive no clue.

DevBiker 07-19-2019 08:32 AM

Quote:

Originally Posted by RodrigoDRT (Post 1011774)
what exactly does single/multi rail ocp does? ive no clue.

http://www.jonnyguru.com/forums/show...f-the-12V-rail

RodrigoDRT 07-19-2019 09:37 AM

Quote:

Originally Posted by DevBiker (Post 1011777)

unfortunatelly i could not understand quite clearly whats said there.

so, i mean, im guessing that most of the connectors on a PSU have a +12v rail, taking the GPU ones as an example, my psu afaik has one cable with 2 6+2 pin connector for my graphics card, im just guessing that each cable has a +12v rail?

then, what actually is this single rail or multiple rail? its confusing really, are they like multiple lines for each of these 6+2 pin? because I have little knowledge in psu workings i couldnt get to a conclusion on that article.

DevBiker 07-19-2019 10:17 AM

A single connector with 2 connectors is NOT multiple rails.
The rail is implemented on the PSU, not in the cable. You may have a rail for each PSU connection (in a modular PSU). It depends on how its implemented.

As noted in the link to jonnyguru, multiple rails is for safety. It prevents any single 12V rail from having too much current. You DO NOT want 1000W (83A) of power going down a single connector!! Multiple rails prevent that.

RodrigoDRT 07-19-2019 10:27 AM

Quote:

Originally Posted by DevBiker (Post 1011793)
A single connector with 2 connectors is NOT multiple rails.
The rail is implemented on the PSU, not in the cable. You may have a rail for each PSU connection (in a modular PSU). It depends on how its implemented.

As noted in the link to jonnyguru, multiple rails is for safety. It prevents any single 12V rail from having too much current. You DO NOT want 1000W (83A) of power going down a single connector!! Multiple rails prevent that.

i see, then if i get this right, is possible that a cheap psu has a single rail (pcb goldy line thinigies) powering multiple (12v) connectors, leading to an overload.

if i get this right, the multiple rails COULD mean that in the aforementioned example, 6+2 connectors have a rail for each one of them, right?

makes me wonder, however, why would theres even a selector for single or multi, seems like multi is the best way to go, no?

DevBiker 07-19-2019 10:31 AM

Quote:

Originally Posted by RodrigoDRT (Post 1011794)
i see, then if i get this right, is possible that a cheap psu has a single rail (pcb goldy line thinigies) powering multiple (12v) connectors, leading to an overload.

Yup.

Quote:

Originally Posted by RodrigoDRT (Post 1011794)
if i get this right, the multiple rails COULD mean that in the aforementioned example, 6+2 connectors have a rail for each one of them, right?

Yes, they'd be separate cables each going back to the PSU rail.

Quote:

Originally Posted by RodrigoDRT (Post 1011794)
makes me wonder, however, why would theres even a selector for single or multi, seems like multi is the best way to go, no?

There are rare and unusual edge cases where multirail can cause problems. And some people insist. Some people also insist that the moon landing was faked and the earth is flat, too. But yeah, 99.95% of the time multi rail is the way to go. Because safety.

RodrigoDRT 07-19-2019 10:43 AM

Quote:

Originally Posted by DevBiker (Post 1011795)
Yup.


Yes, they'd be separate cables each going back to the PSU rail.


There are rare and unusual edge cases where multirail can cause problems. And some people insist. Some people also insist that the moon landing was faked and the earth is flat, too. But yeah, 99.95% of the time multi rail is the way to go. Because safety.

ah thats all great information, ill keep reading on the subject, I think ive found some info about how single rails are literally larger and can carry a higher intensity (amperes) if im right, thus, would make sense if say, on a multi rail mode a line can only handle so many amps and something is drawing more than it can, blowing it up (hyperbole), but i assume multi rail thingies are probably made so they will handle anything up to date

been a while i've been so curious to know how something works, not sure why.

DevBiker 07-19-2019 10:59 AM

Quote:

Originally Posted by RodrigoDRT (Post 1011796)
ah thats all great information, ill keep reading on the subject, I think ive found some info about how single rails are literally larger and can carry a higher intensity (amperes) if im right, thus, would make sense if say, on a multi rail mode a line can only handle so many amps and something is drawing more than it can, blowing it up (hyperbole), but i assume multi rail thingies are probably made so they will handle anything up to date

been a while i've been so curious to know how something works, not sure why.

They aren't necessarily physically larger (lower gauge). They do carry higher current (amps) before tripping. Same wire + higher amps == melting wire. Hence ... multi rail for safety.

Vegan 07-20-2019 01:26 PM

My AX860i has separate OCP for each PCIe cable and EPS12V cable. It can be set from 20A to 40A (default).

The AX860i can move power around as needed just like any modern PSU.

A few cards with 3 8-pin PCIe power are out there which is why my AX860i comes with lots of cables.


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