What is the meaning of TriRails on PSU ? (+12V1,+12V2.+12V3)

[PX7800GT]

Hi every body , the question is about PowerSupply ??
what is the Meaning of DualRails or TriRails ??
for example i see a PSU with these Spec :
TriRails : +12V1 (12A) , +12V2 (22A) ,+12V3 (14A)
what is the differenece between TriRails & SingleRail or DualRails ...??
& which one should i read for using a Video Card , For example a GeForce 7950GX2 needs at least 29A on the +12V rail, so if i want to use that PSU (TriRails : +12V1 (12A) , +12V2 (22A) ,+12V3 (14A) ) wich one of these numbers should i read ?? i`m so confused :?
i will be very thankful for any help... 😀

 

[PX7800GT]

Thank You so much mpilchfamily...
you helped me so much... 😀

 

[jaguarskx]

Hi every body , the question is about PowerSupply ??
what is the Meaning of DualRails or TriRails ??
for example i see a PSU with these Spec :
TriRails : +12V1 (12A) , +12V2 (22A) ,+12V3 (14A)

I just want to let you know that you cannot simply add up all the amps on the three rails of the PSU to determine the total amount of amps all three 12v rails will deliver.

For example, the Antec True Power Trio TP3-550 ATX12V 550W has three 12v rails that is stated to produce 18amps on each as can been seen in the following link:

Picture of PSU specifications sticker.

If you simply add up all 18 amps on the three 12v rails, then you will get 54 amps. That would mean this 550w PSU would produce 648w of power (54 amps X 12v) on the 12v rails alone. No it's not magic, and it is not free energy. Each 12v rail can provide a maximum of 18 amps, but in total the PSU can only deliver 42 amps.

Note the part of the sticker that states the following:

+12v, +12v, and +12v, max load: 42A

Therefore, at most the Antec True Power Trio TP3-550 ATX12V 550W, can only provide a maximum of 504w on the 12v rails. That is also assuming that the most power drawn from the 3.3v and 5v rails will only be 46w; 504w + 46w = 550w.

If your system was drawing 100w from the 3.3v and 5v rails, then the maximum available power on the 12v rails would be 450w or 38 amps (450w / 12v).

 

[PX7800GT]

TanX 8)
I Have a ACBel 550 Watt and it has TriRails (+12V1,+12V2,+12V3)
it has a total of 30A on the +12V (total 360W)
i just want to know if i could buy a GeForce 7950GX2 (need at least 29A on the +12VRails)
ThaX Again 😀