PC Peripherals single-rail smps vs multiple-rail smps

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WingZero

WingZero

Forerunner
found an excellent example of why 1 single 12v rail is superior to multiple rails.
Here's a quote from PC Power & Cooling's website:
Here are the facts: A large, single 12-volt rail (without a 240VA limit) can transfer 100% of the 12-volt output from the PSU to the computer, while a multi-rail 12-volt design has distribution losses of up to 30% of the power supply’s rating. Those losses occur because power literally gets “trapped†on under-utilized rails. For example, if the 12-volt rail that powers the CPU is rated for 17 amps and the CPU only uses 7A, the remaining 10A is unusable, since it is isolated from the rest of the system.

Since the maximum current from any one 12-volt rail of a multiple-rail PSU is limited to 20 amps (240VA / 12 volts = 20 amps), PCs with high-performance components that draw over 20 amps from the same rail are subject to over-current shutdowns. With power requirements for multiple processors and graphics cards continuing to grow, the multiple-rail design, with its 240VA limit per rail, is basically obsolete.
 
But some newer PSU's have the feature to share multiple rails in case the need arise.... Like Corsair HX620 does this....
 
a single rail is generally better because of the 2nd reason u posted above^^

neways, regulations have a max amperage for 6pin connectors.... so graphics cards like the 8800gtx have 2 6pin connectors instead of 1 connector supplying a larger current

thats y multiple 12volt rails with 20amps are also fine
 
racy1 said:
But some newer PSU's have the feature to share multiple rails in case the need arise.... Like Corsair HX620 does this....
Click to expand...

corsair HX 620 is actually a single rail smps ;)
 
booo said:
Triple 12V Rails provide independent reliable power to the CPU, video card and other components with a combined rating of 50A (40A on 520W) maximum! Advanced circuitry design that automatically enables power sharing between the triple +12V rails in an event of overload on any single +12V rail.

Welcome to Corsair :: HX Power Supply Product Information
Click to expand...
thats what corsair says..but...

JonnyGURU.com - Power Supply Reviews and more! - Reviews - Corsair HX620W 620W
Read tthe addendum at the end of review...

"So it is my opinion that we essentially have a single 12V rail PSU here. Certainly there is nothing wrong with this given the problems high end video cards have had with getting enough power from a single 12V rail when the OCP is set to the typical 240VA limit. But we do lose the advantages of multiple rails such as protection from damage to one rail from a short on another and the simple "filtration" of noise introduced from one rail to another."
 
yes titana is right.hardwaresecrets.com also reviewed it and frm tht it's clear that corsair hx620w single rail.
 
^^power supply reviews generally have them opened up and examined so they always say if its a true single rail or multiple rail

i think the hx620 is single rail but the vx series psu in smilar range (550 i think) is 2 or 3 rails
 
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