What does each rail actually do?

thealmightyone

thealmightyone

New Member
I'm just trying to decide between 2 similar psu's:

The Enermax 600W Noisetaker; 2x18A@12V, 45A@5V, [email protected]

The Enermax 620W Modular; 2x22A@12V, 32A@5V, [email protected]

As you can see, the modular is superior on the 12V rail, but is beaten on the 5V and 3.5V rails. What would help me to decide is to understand the purpose of each separate rail, rather than simply be told "get this", "get that".

Thanks in advance.
 
5v rails control power to parts of the harddrives. A lot of the PCI cards and lower end graphics cards use the 3.3v rail. erm.... doesnt the 12v contorl drive motors and things like that, im not sure, oh and most pentium 4 cpus use the 12v supply for stability, ya know that extra 4-pin plug that youplug into your mobo...

dragon

*EDIT* - quote from another forum

Your cpu, northbridge, southbridge, gpu, ram, etc. run off 3.3V

ICs, hard drives and CD-Roms run off 5V.

All 12V is pretty much used for is fans. Thats why the 12V rail is so weak. Read the specs of your PSU and you will see that the 12V rail is only capable of like 40 watts, 12V is usually undervolted too but thats OK because fans are perfectly happy at 11.5V.
Click to expand...
 
dragon2309 said:
5v rails control power to parts of the harddrives. A lot of the PCI cards and lower end graphics cards use the 3.3v rail. erm.... doesnt the 12v contorl drive motors and things like that, im not sure, oh and most pentium 4 cpus use the 12v supply for stability, ya know that extra 4-pin plug that youplug into your mobo...

dragon

*EDIT* - quote from another forum
Click to expand...

i dont like the quote you got from the other site... its not strictly accurate, technically the 12 volt rails needs to be and is the strongest rail on a PSU. All high power parts are run off the 12V rails and as such strong 12V are important for general system stability
 
I'm with Hairy Lee - that quote from the other forum seems to diminish the importance of the 12v rail, where in fact it's the most important. It is used for far more than 'just fans'.

Edit: Much better pic, by the way. :P
 
So, should I reverse my decision and opt for the Modular? Is the sacrifice on the 5V and 3.5V rails worth the gain on the 12V rail?
 
go for the one with the stronger 12V rails... this will ensure that you Graphics and mainboard get all the power they need
 
Kind of off topic, but about rails. Can you connect adapters of different voltages to their corresponding rails on, say, a hard drive, and it run normally? (rather than connecting it to the power supply) I know this seems pointless, but it's knowledge I need for a project that isn't strictly computer-related.
 
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