Dividing the load among connectors on PSU, or the same as if on less connectors?

uplink777 · July 12, 2017

Hey there

This question've been bothering me for two decades now, but since PSU's are still evolving, it's hard to get a clear answer. I'm having Be Quiet! Dark Power Pro 11 850W atm. in my "future" computer. And my question goes as follows.

1. I have 2 PSU cables. Both have 1 x 8 pin and 2 x 4 pin cable. Thus 2 x 8 pin. Does it matter, whether I use two cables, with 16 + 16 pin cables, and only use the 8 pin rails from each, thus leaving 4 + 4 on each vacant, or can I use just one cable [for the sake of better cable managment]? The 7900X is a power hungry beast, and as I saw it can suck up to 500 watts from the wall, thus, I'm not sure if the rails are connected within the PSU, or not at all.

2. I have SATA cables, like 8 of them, each can handle up to 4 devices. My question goes as follows. I have one high-watt pump [Laing DDC] + case fan hub [Be Quiet! Dark Base 900 Pro] with attached 4 fans so far [am planning at least one more], where each of the fans have around 3 watts at peak [12V x 0.202A as they state on the website - Corsair ML140 Pro] and 2 SSDs, Intel 750 U.2, where each SSD sucks up to 20Watts. That's around 50Watts of load for one rail. Is it better to distributed this load?

Thank You for Your eventual advice,

Kind regards

Bryan

mariushm · July 12, 2017

The wires are arranged like this in Dark Power Pro 11 850w :

Cabling - BeQuiet! P11-850W
Type of Cable	Length from PSU	+12V Rail
20+4 pin ATX connector	610mm	12V1
Modular Cables
5.25"+5.25"+5.25"	600+150+150mm	12V1
5.25"+5.25"+3.5"	600+150+150mm
5.25"	600mm
SATA+SATA+5.25"+5.25"+3.5"	600+150+150+150+150mm
SATA+SATA+SATA	600+150+150mm
SATA+SATA+SATA	600+150+150mm
4+4 pin CPU	700mm	12V2
8 pin CPU	700mm	12V2
6 pin PCI-E	600mm	12V3/ 12V4
Dual 6+2 pin PCI-E	600mm 600mm
Dual 6+2 pin PCI-E	600mm 600mm
Dual 6+2 pin PCI-E	600mm 600mm
Auxiliary Cables
OCK switch	700mm
5.25" Fan + 3 Pin Fan	600+150mm
5.25" Fan + 3 Pin Fan	600+150mm
5.25" Fan + 3 Pin Fan	600+150mm
5.25" Fan + 3 Pin Fan	600+150mm

Using one cpu 8 pin connector per strand of wires from the power supply would be better in your case.

More wires between power supply and motherboard is better (there's less energy lost in the wires, the wires heat less etc)

The 7900x and socket 2066 are in general very power hungry and the vrms also heat up a lot, you can read a lot about it here: http://www.tomshardware.com/reviews/-intel-skylake-x-overclocking-thermal-issues,5117-3.html

The cables used in SATA strips can generally handle about 10A on each voltage wire, so around 120 watts of power from 12v, around 50w on 5v , around 35w on 3.3v (almost never used in PCs) and each sata connector in theory can do 4.5A on each voltage so about 55w on 12v but generally you wouldn't want to go over 30 watts on each sata connector. Basically everything you mention barely uses 20 watts (less than half the maximum capability of each sata connector)

Also note that your fans will use 12v while SSDs will probably use 5v mostly ... so you don't add the power used by SSDs to the power used by fans, they're different voltage lines.