AX1600i for 4x2080ti

Hello, good night everyone, I have a question and a problem regarding how I should connect my equipment, let me explain.

My computer consists among other components of an Asrcok X399 Taichi motherboard, 4x2080ti and the power supply as the post title indicates is an AX1600i, as you can see in the image that I attach, this and other AMD X399 series motherboards request Connect a third cable to power the motherboard when more than 3 GPUs are connected, but the power supply does not have a native cable or output.

Neither does the motherboard manual say which is the correct way to connect it, I am afraid to do it incorrectly since the only outputs I have to feed that third connection of the motherboard would have to be through a molex that is the only thing I have free but I don't know if that is correct or I can create a serious problem.

The other doubt is referring to cables compatible with another source since I want to change the ones that come with the source itself for other better-looking and more comfortable and not so rigid since it depends on what configuration it is sometimes difficult to handle the cables that come standard, I found this pack on Corsair's own page (https://www.corsair.com/es/es/Categor%C3%ADas/Productos/Accesorios-%7C-Piezas/Componentes-para-PC/Fuentes-de-alimentaci%C3%B3n/premium-individually-sleeved-psu-cable-kit-pro-package-type-4-generation-3-config/p/CP-8920155#tab-overview) but when I enter the specifications of this product the AX1600i does not appear as compatible while in another of the points it says that it is Type 4 Gen. 3 Individually Sleeved Cables, the information is a bit confusing, because if I am not wrong, the type 4 cable is the one used by the AX1600i.

Any help is appreciated.

Thank you.

Kepa.

http://imgfz.com/i/Sdjnpkc.jpeg

Hi Jonnyguru

Thank you very much for answering me so quickly.

Yes, as you say, the source comes with a total of 8 PCIe cables. Six with two PCIe connectors (total 12) and two with one connector each (total 4), but they told me that each channel of 4 pins of the GPUs, that is 8, had to power them individually, which is not advisable to do it using double PCIe to feed a single GPU, I do not know if it is correct or if it really generates any problem or inconvenience to the GPUs or the whole, that's why all my ports are busy feeding the GPUs, hence the 8 PCIe cables (including the double even if the double pair are not used) have them in use.

The problem is that I have always been told that I must connect it like this, without using the double PCIe connections for a card and I don't know if that can really be a problem when feeding them as it should, I would not want to have a problem with this . I don't know if connecting a GPU with a two connector PCIe cable is the same as connecting two individual PCIe cables separately.

The other question was regarding the compatibility of the cables that I have put there for my power supply.

I await your answer Jonnyguru, thank you very much for the help.

A greeting.

Kepa.

So, what you want to tell me, is that there is no problem in feeding this configuration with the double PCIe cabling? It is not clear to me if you affirm it or if because there are cables of that type it is supposed to be possible, if so it would be more logical that all the PCIe cables were double, right? I ask.

Forgive my ignorance, but so far I have not found a conclusive answer about this, that is, that I can directly use these cables on the 4 GPUs without any problem with load on all the GPUs? As you tell me, I could power the 4 GPUs with the pig-tail cables and thus I would only need 4 PCIe cables of this type connected to the power supply, is that correct?

Regarding scalability, I do not know if you speak specifically, in my case, it is not the case that you propose, my 4 GPUs work at the maximum capacity of each one, calculating simulations and render, and if I use x4 the power, measured in wall socket when the 4 GPUs use rendering engines such as Cycles or Octane, only working the 4, the consumption peaks of all at the same time rises to 1000W.

I just want to be sure that there is no problem in connecting it like this or some reasoning why there is no problem, nothing more, but I never find an answer to whether this is correct, neither a manufacturer of power supplies, nor that of the motherboard , neither the one of the graph, not even in forums, hence my concern.

Thank you very much Jonnyguru.

When I mean that they recommend it or they tell me to use separate cables, as a quote I put this link where I was also looking for information about it and this user cited something similar, I repeat I speak from ignorance but I cannot find an answer in which I Explain why you should have no doubt that feeding 4 x2080ti running all of them to the maximum of their capacity at the same time, with this type of cabling with a double PCIe cable does not involve risk:

A couple of weeks ago I've built my first PC with a modular PSU (Corsair 850HX Titanium) and - trying to be a good person - I've tried to keep the inside of my shiny new case (NZXT H700i) as clean as possible. In other words: I avoided cables as much as I could ... so I used a single PCIe power cable from the PSU via daisy-bridge for the Asus RTX 2080 Ti Dual OC Advanced edition.

Result? Severe instability in multiple games - from Assassin's Creed to the latest iteration of Call of Duty. Until it dawned on me that my RTX might want two dedicated cables from the PSU ... and guess what, the stability issues vanished instantaneously.

That kind of issues is often caused by people using extension leads with thin wire gauge.

Under load, the 12V will droop quite a bit and they will have instability issues with GPU crashing at random.

When using just the cables from the PSU (or good extensions), the difference between 1 pig tail and 2 cables is negligible.

I checked on my 2080 when connecting a second cable : the lowest value i had for 12V under load was 11.7 before, and 11.85 after (from HWinfo) with extensions.. that's peak values. most of the time it's between 11.9 and 12 in both configurations.

A colleague i know who uses cheapo thin extensions has his PCIE 12v dropping to 11.3V

Just to say, the whole chain counts, not just the source :)

Thanks Jonnyguru,

Sorry but I have not understood what you are saying, I have lost a lot in the configuration you propose, I do not want to seem heavy but it is the first time that I have seen myself with this type of problem and my ignorance in this aspect is what it is, no I know very well what you propose to me.

On the other hand and this in particular, as a comment, I do not understand very well if there is so much demand for connections and consumption, this being Corsair's top power supply and not only with Corsair, as they do in all the configuration of Workstations that I see in the network, stores or youtube to make these configurations? I have never been able to see how these settings connect, this is a headache.

Thank you Jonnyguru

But, if I use 4 individual PCIe cables, I connect these to each of the graphics cards individually and I take two pig-tail cables to connect as you say only two GPUs into the second power connector, I still have two cards without full power, Right?

The first connector of the 4 GPUs are covered by the individual PCIe cables and if I connect two into the second power connector of only two GPUs the other two would still need to be fully powered, there are 8 connections and with your explanation I add 6, as you just finished to describe it.

The problem really comes from having to feed the motherboard in an extra way, because the source with all the PCIe cables individually, feeds it without problem, but of course I do not know if having to give all these laps for that extra connection of the plate is I could feed in another way, safely.

In this configuration it powers each titan rtx GPU individually without any pig-tail, but I don't understand how it does it.

[ame]

Sorry, but no matter how much I read what you tell me, this is what you put and it is what I understand.

"You take two cables with two connectors on them. You plug each of those cables into two of the second power connectors of two cards."

You say that I only connect in two of the cards but if I do that I leave two without finishing connecting them completely. You don't mean to say that those two pig-tail cables are distributed between the 4 and not between two of the cards as you have put?

On the other hand, I do not understand why in all the configurations that I see they feed the 4 gpus with individual cables as in the video that I show you, something does not fit me, they do it somehow.

http://imgfz.com/i/RPJQXiL.jpeg

That is if I understand it as you have drawn it but you have written that I connect it only on two cards.

Even so, something escapes us because in all configurations they connect them individually.

Nor is it necessary to answer like this, I have understood one thing and you have drawn another, I thank you very much for the time you are spending in explaining but it is not necessary to put it like that, you had written one thing and drawn another, it was not my intention that you take it that way but I think that if you look at what you have written you will understand that I could not understand what you were saying.

"You plug each of those cables into two of the second power connectors of two cards" I understand that you say 2 in the text and not 4 as you draw.

Don't worry anymore, thank you.