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View Full Version : What are rails in PSUs?



TheWolf85
03-11-2007, 10:53 PM
Ever buy one of those games that turned to out be way more expensive than $50 because you had to upgrade your computer just to play the damn thing? Company of Heroes is one such game to me. I've updated my video card (from a x800Pro to a x1650Pro), added some more memory (doubled my memory with 2x512MB Crucial sticks), and now it looks like I'm going to need a new PSU to power it all. This game is getting pricy...

I've been doing some reseach on PSUs and the whole "rail" thing is utterly confusing to me. I don't understand what multiple 12V rails physically mean. If there are more than one rail, does that mean that there are more that one cable attached to each 12V rail? I think I understand that the devil with PSUs is that the actual amperage delivered by each "rail" is a lot more decieving than what is being advertised. Most of the time only the MAX output is listed, while the steady state currently is usually about 85% of the max. If there are multiple rails, the output of each rail is limited by the total amount of amperage allowed out of all the rails together (IE, in a PSU with two rails with a max output of 20A each and and total combined output of 35A, one rail is limited to only 15A if the other rail is running at 20A). I don't understand why this is bad, I just get the sense that it is. Again, this stems from me not understanding what a rail really means. If someone could explain this to me, I would be very apprecative. I really want to play a whole game of COH sometime within the near future and I don't want to waste any more money. Thank you.

Rob
03-12-2007, 07:45 AM
You probably know more about PSU rails than me. What I do know is that not all PSU's are the same. You can't just buy one for its wattage, you have to buy quality. The power supplies I recommend are Antec and Enermax. If you buy something of sufficient wattage within those brands then you'll be ok.

DemonicDerek
03-12-2007, 07:45 PM
True, but what does the rail mean?

Amosmoses33
07-27-2007, 12:54 PM
ive been wondering this too...the Hiper psu reference rails. what does that mean?

see this link i just found, hope it helps

http://www.playtool.com/pages/psurailhistory/rails.html

gtrasi
08-27-2007, 12:14 AM
Here's more to add to the confusion...

Recently i cam across mobo that require 8 pin CPU power connector besides ATX 24 pin power connector!

I hav only seen 4pin cpu power connector and i hav searched all over the net to find 2 mobos , one from jetway(M2A690GDG) and another from Asus( also AM2 based) that hav 8pin cpu power connector.

But whts worring is I still cant find a SMPS that actualyy has 8pin CPU power connector rail!

So whts am I missing here?

Amosmoses33
08-27-2007, 08:48 AM
My power supply had an 8 pin and a 4 pin and my mobo had an 8 pin with a block covering 4 of the pins making it a 4 pin. Corsair HX620

koganinja
08-27-2007, 01:37 PM
evga 680i has all 8 and i got all 8 plugged in go look in the my rig pics

DemonicDerek
08-28-2007, 01:48 AM
Go to www.3dgameman.com and look for a review on a Powersupply and in all of his power supply reviews he explains RAILS.

Amosmoses33
08-30-2007, 08:56 AM
my link above explains rails as well. :)