PSU Help needed

mikexz

Reputable
Aug 30, 2014
9
0
4,510
Hi everyone

I am ordering a pc with these specs:
Gtx 780 or 780ti still undecided
16 GB RAM
i7 4790k 4.0-4.4ghz

i would like to either get a 750w EVGA Supernova or 850w SuperNOVA. I know the 850w might be too much but the 750w that is being sold by the place I am getting from is split into 4 12V rails rather than a single 12V rail like the 850w is. Should I be concerned that the 750w is 4 12V rails rather than a single, I read somewhere on here I saw someone say that to run a 780 or 780ti you need about 42A, the 850w supplies that more than that, but the 750w has 20A split up over 4 12V rails. Is there a difference between a single rail vs 4 12v? Should i be worried about this? Any help is greattly appreciated
 

InvalidError

Titan
Moderator
The 42A rating is for the whole system and even then, it is still a considerably exaggerated figure: the 780Ti uses less than 330W peak or about 27A. Split between two rails (two PCIE power cables on two separate rails), that's about 14A peak each.

The disadvantage of multiple rails is that it is easier to accidentally trip individual outputs. The disadvantage of a single huge rail is that a short may fail to trip over-current protection and fry the wiring. Pick your poison.