Rails, large one or small multiple ones?

M

maverick212

Limp Gawd
Joined
Nov 26, 2004
Messages
237
Corsair CMPSU-550VX has one 12v rail at 41A, 550W.

OCZ StealthXStream OCZ600SXS has four 12v rails at 18A each, 600W.

XCLIO GREATPOWER X14S4P3 has three 12v rails at 18A/18A/16A, 550W.

To power: Q6600, 4GB 4-4-4-12 G Skill (2-4GB added later), Nvidia Quadro 570, Seagate 7200.10 250 gb (another drive later), Gigabyte GA-P35-DS3P Rev 2.0, DVD/CDR burner, 2 120 case fans, I think thats it.

Basically...is it really better to have those smaller rails vs one larger rail? No matter how much reseach I've been doing, I've been finding different opinions :(
 
Multiple rails are a result of the IEC 60950 safety specification, which allows no more than 240VA on any single wire. The idea is that if something shorts or burns, there is, at most, 240VA available to cause damage. At 12V this means no more than 20A. In order to supply more than 20A of 12V power and comply with IEC 60950, you need multiple rails.

It's not because multiple rails are somehow better for the PC. (Well, except in the case of something shorting or burning, in which case it will likely not matter if the power supply is IEC 60950 compliant or not---240VA is still quite enough to fry computer circuits.)

I chose a single-rail power supply (a Silverstone Decathlon) primarily for that reason. Also because it's what PC Power & Cooling does, and PCP&C is a long-standing and well-recognized leader in power supplies.

That said, though, it really doesn't make a whole lot of difference if you use multiple rails or not. The only difference is maybe some extra planning. With a multi-rail PSU it's best to know what rails power what connectors and plan accordingly (so you don't have one rail overloaded and another barely used, for example).
 
rsquared said:
Multiple rails are a result of the IEC 60950 safety specification, which allows no more than 240VA on any single wire. The idea is that if something shorts or burns, there is, at most, 240VA available to cause damage. At 12V this means no more than 20A. In order to supply more than 20A of 12V power and comply with IEC 60950, you need multiple rails.

It's not because multiple rails are somehow better for the PC. (Well, except in the case of something shorting or burning, in which case it will likely not matter if the power supply is IEC 60950 compliant or not---240VA is still quite enough to fry computer circuits.)

I chose a single-rail power supply (a Silverstone Decathlon) primarily for that reason. Also because it's what PC Power & Cooling does, and PCP&C is a long-standing and well-recognized leader in power supplies.

That said, though, it really doesn't make a whole lot of difference if you use multiple rails or not. The only difference is maybe some extra planning. With a multi-rail PSU it's best to know what rails power what connectors and plan accordingly (so you don't have one rail overloaded and another barely used, for example).
Click to expand...

+1

What I would be concerned with is the overcurrent and overvoltage protection circuits and how they are implemented on BOTH kinds of supplies. But that is almost impossible to find out. I dont care (well, I do some) if a $100 PSU goes belly up but I dont want it taking the rest of my machine with it.
 
Corsair CMPSU-550VX has one 12v rail at 41A, 550W.
Note that the combined power on the +12 is 490W = 41A
5 year warranty

OCZ StealthXStream OCZ600SXS has four 12v rails at 18A each, 600W.
Note that the combined power on all the +12 rails is 580W = 48.3 Amps (not 64A)
3 year warranty

XCLIO GREATPOWER X14S4P3 has three 12v rails at 18A/18A/16A, 550W.
Note that there is no "combined power" listed for the +12V.
don't care about warranty, I don't like it, don't know why, there it is.




I like the OCZ or the Corsair. AFAIK the Xcilo may be good to, I just don't like it and cannot say why /shrug. I have a VX-550 and it is very quiet and running a bunch more stuff than you listed, DQ6, E6300@ 3.3GHz, ATI X1900GT, water cooling pump, 5 x Hitachi drives, CD burner, floppy, 4 x 1GB (well 2 x 1GB now, could not maintain my OC with 4 x 1GB) couple of lights, 3 x 120mm fans, 5 x 80mm fans, 4 x 40mm fans, 1 x 50mm fan. (not sure I have enough fans, that could be an problem ;), but they are all low volted or on a controller so it is very quiet) The power supply is dead quiet and the output exhaust is not even warm. Heavy as lead. I love it. I went with the Corsair because it had 6 SATA connectors for my drives and was reviewed well by jonnyguru plus the warranty plus the sticker is on the top out of sight. I recommend you see if there are reviews for that OCZ on an actual load tester and pics of the internal build quality. I would also watch for ripple measurements on the OCZ, its 700W brother has an issue with ripple as well as the 600W FSP supply I think the OCZ is based on. This may or may not still be a concern, I cant keep up with who really builds what these days.
 
rsquared said:
Also because it's what PC Power & Cooling does, and PCP&C is a long-standing and well-recognized leader in power supplies.
Click to expand...

Only AFTER they had done the split +12V rail thing and screwed up by putting all of the PCI-e connectors on the same rail. Instead of doing what SilverStone did and going back to the drawing board and re-arranging the connectors and what rail they get power from and re-releasing a newer version.
 
I suggest a large single rail. No worries at all about rail distribution.

HX 520, anyone?
 
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