Topic: A little help deciding how to power everything using 2 psu. (Read 337 times)

This is a riser with 6-pin power:



You don't normally buy any cables to power risers, you just power them straight from your PSU. If you have extra 6-pin pci-e connectors (and you probably will, since you're going with PSUs that have 8x pci-e 6+2pin connectors, and only using 6x of them to power your Vega's, leaving you 2x extra) — then you can use them to power the risers. And forget about sata cables completely, they're bad, mkay. Just because you're using some adapters on your sata cables doesn't make them legit, they're still crap no matter how many adapters you connect to them, the sata connector itself will still be the weakest link and the current doesn't somehow magically go around it when you put an adapter on your sata connector.

It's not that complicated, just google reviews of a few PSUs that are available to you, see what kinds of cables they come with, and figure out a way to power your cards and risers without using sata power or putting more than one riser on each power cable. Then buy appropriate risers for your PSUs. For example, you could buy 4x risers with molex power and 2x risers with pci-e 6-pin power. Most PSUs will have two separate cables with molex connectors so you can power two risers with them, and the third riser will be powered by the pci-e cable from the PSU. Same for the 2nd unit, and that's it, you've got 6 cards and 6 risers powered with two PSUs. Don't just buy stuff though before researching it, there's a ton of reviews for any decent 1000W+ PSU out there, all those Corsairs, Seasonics, Coolermasters, EVGA's etc, they're all reviewed in detail with all the cables they come with listed.

The first one - since ~15.09. The second is fresh. Drawing around 1100W from the wall last I checked.

Directly as psu -sata cable +connector+ the first cable on the riser -riser cable ?
This seems exactly my case here : https://www.reddit.com/r/EtherMining/comments/6qpsfx/risers_6_pin_to_6_pin/

Or i am missing something .Thanks for all the help.

Pic to be sure lol

You don't need to buy any such cables, and did you even see the risers with pci-e power? They're all 6 pin pci-e, not 8-pin. You power them directly from your PSU. As I said before, this thing from your link to ebay is for people with old PSUs which only have 6-pin pci-e connectors, but their new GPU needs an 8-pin pci-e connector. In order to power that GPU with their old PSU — they'll need that adapter. There's absolutely no use for such a cable in your case.

I am not sure if you are speaking if i need them for my gpu's or risers.
Well corsair website doesnt say how many cables they provide you with so i will have to give them a call tomorrow.

I was going to buy them to power the risers directly and avoid all the sata/molex drama .

Do you know if a 6pin to 6+2 pin is fine to power risers directly from the sata ports of the psu.

And yea man prob going for the corsair since it's cheaper as well

I don't understand the logic behind this. There is no power "communication" between the risers and the mb, you only connect them with usb/pci-e data links. And there's also no power connection between your sata hdd and the motherboard. I can understand however how powering the riser with one PSU, but the gpu you put into that riser with another PSU, might not be ok: your graphics card will basically have two different power sources, which will have slightly different voltage. Same with atx 24pin and eps 8pin, doesn't seem ok to power them from different PSUs. I'm no expert on electrical things though, so you'll definitely want to hear other users' opinions on this.

Sata risers are not considered a best practice at all, no matter how you connect them. The cables' quality is up to the PSU manufacturer, if it's a decent PSU then the cables themselves are probably alright for 75W. The problem is the actual sata connector, it's rated for a lot less than 75W. So using any sata connectors at all is generally not a good idea.

Why would you need them if your PSU has enough 6+2 pci-e connectors (providing you go with Corsair or similar unit with 8* 6+2pin)? They are for people that only have 6-pin connectors coming from their PSU and want to connect a card that has 8-pin connector.

1)Quoting from another forum which i have the same questions :
All risers, MB, and HDD should be off of the same power supply or you run the chance of having grounding issues between the two power supplies. No more than two risers per sata connection is a best practice.

2)There are numerous amounts of people commenting on reddit about melted cables, here is an example : https://www.reddit.com/r/EtherMining/comments/6qpsfx/risers_6_pin_to_6_pin/

Simple cables man like those ; https://www.ebay.com/itm/6-pin-to-6-or-8-pin-6-2-PCIe-adapter-graphics-card-power-cable/191149463647?epid=1304711133&hash=item2c8165585f:g:vnkAAOxy4YdTPmjD
or this
https://www.ebay.com/itm/12-PCI-Express-6-Pin-PCI-E-Power-Extension-Cable-Male-to-Female/310963827808?hash=item4866e37460:g:UGkAAOxyBPZTe1nk

Each card has to be connected from the same PSU as its riser. And you need to connect the MB with both 24-pin ATX and 8-pin EPS coming from the same PSU. I think that's all that matters.

What cables are you considering to buy? I couldn't understand this sentence. You don't need to buy any cables for your risers or PSU. The risers with molex (4-pin) and pci-e (6-pin) connectors are both fine, it's the ones with the sata connector that are not good. You can mix and match different risers obviously, depending on the kind of PSU(s) you have, for example you could buy 4 molex risers and 2 6-pin pci-e risers.

There are different server PSUs, some are very noisy, and some are pretty quiet.

How long are you running those rigs?
What's the total wattage of your rig?

Trying to avoid server psu because everyone says it makes so much noise .I will just return it and get 2 corsair ones as the third comment suggests , they will be cheaper as well.

You are right about the first part .Well i hear problems if u dont power the risers from the same psu u power mobo ,cpu ,hdd not sure if that counts .
I will go with the corsair psu the guy in the third comment link to be sure . You are right evga is weird for this project.

I am actually considering buying 6pin cables to power the risers directly riser 6pin cable psu  since i assume this is the safest way?

I am using 2x Corsair RM1000X on both of mine 6 vega rigs.

Nothing special about how to manage the cables - PSU 1 powers CPU, 2 molex to the MOBO, 3 Vega and 3 different Sata cables to the v007 risers. PSU2 - powers 3 VEGA, 3 Risers (SATA) and the SSD.
The good thing about the corsairs is, that the PSU comes with 4x 8pin+ 6+2 pin cables, so if you wish you can power 4 vega cards without any extenders.

ATX powersupplies are too expensive, I usually go with the 240v ones from parallel miner, but I think they have some 120v's if needed. I'd check them out. You can even use your current 1600w and add in the server psu

Isn't it 6x 8-pin connectors and 2x 6-pin connectors — 8 pci-e connectors in total over 6 cables? That's what EVGA site says. I don't get it why you keep buying those EVGA PSUs for your Vega's though, their cabling is weird and not very convenient for your GPUs. Something like Coolermaster V1000 would be easier to connect (or any other similar PSU with all pci-e connectors being 6+2 pin, instead of some being just 6-pin as EVGA does it. It's fine for cards with 8+6 pin power connectors, but not so much for Vega's with their 8+8 connectors.

Anyway, just divide the whole load as evenly as you can between two PSUs. One PSU powers the motherboard, cpu, 3x GPUs with those 6x 8-pin connectors and 3 risers with whatever you have left. The 2 molex cables, I suppose, is all you'll have left? Will have to share them between 3 risers. Another option is powering one riser with sata connector, but I'd rather go with 2 molexes for 2 risers from the same single cable (though if it's 18 awg then neither is the best way to power the risers). And the 2nd PSU powers the remaining 3 cards the same way + the hdd.

Saphire 6x vega 64,asrock pro btc h110.
Had one 1600w p2 psu by evga but decided it's too much of puzzle to power 6 vegas and i will return it and get 2x1000w g2 by evga as well.

The psu's has 6 8pin slots and 6 6pin slots.

Some people say to power mobo,cpu,hdd and all risers from one psu or u will face issues
while others say to power the risers from the psu u are powering their gpus .

Anyone can throw some insight?