Question about Multi-Rail PSU

[ianalberto]

hi, i want to ask a question about a Multi-Rail PSU. For example i have the HEC Cougar SL-500W with 2 12v1-19amps & 12v2-20amps. It has 8(4+4) ATX Pins. What if i connect it to my Motherboard which only requires 4pins, will i get only 19amps or the two amps combined?

 

[JOHNN93]

it should be combined but that is the max value the rails can handle.
12*20 = 240 watt
12*19 = 228 watt
if you do this with all the rails and you add them up you will see that this is the max output your psu can provide.
you dont need to get into detail about the rails you can split the 8 pin conector.

 

[ianalberto]

hmm, so what would you recommend for a PSU? a Corsair VS450 w/ a Single 12v-34amps or HEC Cougar SL-500W w/ 12v1-19amps and 12v2-20amps? this is the only PSU that fits into my budget and do you think both PSU would run HD 5570?

 

[unksol]

it's limited to whichever rail it's on, which is irrelevant. if your motherboard only has a 4 pin that's all it needs, and all 8 pins are going to be on one rail anyway. There's also no way your motherboard and CPU need more than 240W on a board with only a 4 pin connector

 

[JOHNN93]

more rails the better it will be.500 watt should be good for your system go with your budget and personal like.if you have basic system and acouple of fans it whould require near 350 so the gpu should not need more than 100 watt at max
amd require a 450 watt

 

[ianalberto]

can i make things clear? if i bought the Cougar SL-500W PSU and uses only the 4pin in the ATX Connector i can get the 39amps even if the rails are split? is that right?

 

[JOHNN93]

you are not to be concerned about the rails or amps.
the 4 pin conector should not consume more than 5 amps at max.if it was to exede that number you could kiss your pc goodbuy.
but lets say yes it needed all the 12 volt are soldered together in the power supply which means you whould be able to get the 39 amps from one conector.this will never happen but in theory it is possible.
as for the gpu if a gpu requires 250 watt what whould have happened then ? well pure physics Kirchhoff's current law (KCL) if you know basics in electronics this should befamiliar to you😉

lets say i4 is not existent and no resistors are on the diagram.
lets say i2 5 apms and i3 5 apms are your 12 volt rails thye both conect together you whould have 10 amps on i1 or power conector.
if i4 was not in use like the 4 pin conector then there whould be no current going through it so both of them whould have went to i1 again.