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Discussion Starter #1
Noob question:

I am building a Threadripper 3960x PC.
In the end it will have two RTX 2080 Ti and one RTX Quadro 4000 cards plus M.2 SSDs and water cooling.

My question:
The board has one 24 pin power connector and two 8 pin ones.
Do I need to feed:
- none
- only one
- both
of the 8 pin connectors from the PSU?

I found info about adapters from 4 pin to 8 pin etc. but not clear information if / when somebody needs the extra power from those connectors.
 

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You will need to use the 24 pin and one of the 8 pins you dont need the second 8 pin unless you are doing really heavy oveclocking
 

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Discussion Starter #3
Ok.
So, the second 8 pin is only adding more power in case draw from the CPU is to high, right?
 

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Noob question:

I am building a Threadripper 3960x PC.
In the end it will have two RTX 2080 Ti and one RTX Quadro 4000 cards plus M.2 SSDs and water cooling.

My question:
The board has one 24 pin power connector and two 8 pin ones.
Do I need to feed:
- none
- only one
- both
of the 8 pin connectors from the PSU?

I found info about adapters from 4 pin to 8 pin etc. but not clear information if / when somebody needs the extra power from those connectors.
So, on normal mainstream platforms, and even most Intel HEDT Platforms, the second 8 Pin is not necessary. With the Threadripper 3960x you will be fine using just 1 EPS (The 8 Pin Power Cable) for just about everything you do. No matter what the 24 Pin Power cable will need to be plugged in.

Just for some background for you.

They include 2 8-Pin power connectors on High End boards for people who intend to do Extreme Overclocking, anything from pushing as much power through the chips under normal ambient cooling, to the really high end Sub Ambient Liquid Nitrogen Cooling. Thats when having the 2nd 8-Pin will come in handy.

The CPU gets all of its power from the EPS Connector, where as the 24 Pin Power, powers pretty much the rest of the system. The EPS Power theoretical max (before overpowering the cable itself) is 336 Watts. According to this Article on AnAndTech.com ( https://www.anandtech.com/show/15044/the-amd-ryzen-threadripper-3960x-and-3970x-review-24-and-32-cores-on-7nm/2 ) the 3960x will draw anywhere from 6 to 13 Watts per core at Stock Operation (This includes AMD's Normal Boost Functionality). This means even if you Per CCX Overclock and Push every core pretty far, the most you are looking at will be around 312W on the CPU. While thats high, thats still under the 336 Watts that the EPS Rail can comfortably handle. Realistically if you are not CCX Overclocking, and just letting the Boosting Algorithm do its thing, then AnAndTech saw the 3960x hit only about 270 Watts max on the CPU Package, so it looks like you will be fine with just one plugged in.

That said, it also depends on your Power Supply and how well it handles delivering high wattage. If you were to plug both 8 Pin Cables in, your power supply and Mobo would most likely balance the wattage between the 2 EPS Rails, and you could conceivably have better efficiency, and less stress on one of the rails, whether that would amount to better stability though is questionable.

Regardless, if you only have 1 EPS Cable on your Power Supply, don't worry about it, just plug the one in, and as long as you are trying to push your chip to its Max Overclock, you have nothing to worry about. If you have 2 EPS Cables available to you, then there is no harm in plugging them both in, it most likely won't do anything for you, but it also definitely won't negatively affect you, I just wouldn't worry about it if you don't have one, as it will boot and work just fine with just 1. Hope this helps!
 

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Ok.
So, the second 8 pin is only adding more power in case draw from the CPU is to high, right?
That is correct, and it appears your board is definitely set up to balance the load between the 2 connectors. So you would conceivably see a benifit when Overclocking and really pushing the chip to its max, to having both plugged in, simply because of how your board is designed. But again, especially if you are not Pushing your Chip to the Max, it will do just fine with just one. Just plug your EPS Cable into the one Labeled "ATX12V1".

Can't wait to hear about your experience with your new build is!
 

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Discussion Starter #6
Many thanks guys. Got some vague info like that from searching, but this explains it quite clear.
 

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Many thanks guys. Got some vague info like that from searching, but this explains it quite clear.
Glad to help. I know its damn annoying. Just about 6 years ago, when I went to build my first HEDT system, I hit the same exact dilemma. I had an Asus board with 2 8-Pin power cables, and the manual didn't say jack about if I should use both or not. I was an experienced builder even then, but had never come up against that before. I searched long and hard and couldn't find any concrete data on it. I ended up just trying both, and both worked and I saw no difference between using 1 or 2. Over the years of talking with engineers I came to understand what the second EPS Connector was for, but I still remember how annoying it was when I was knee deep in throwing together my rig and realized the manual didn't inform me on whether or not I needed 2 EPS. The manual helps with Ram Placement, Panel Connectors, which Sata Ports and PCIE Lanes to use, hell it will even guide first time builders on Building the damn PC, but I have yet to come across a manual that clearly explains the damn EPS Connectors. So stupid. Maybe one day...

Anyways, I hope that helps man! Good Luck!
 

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Discussion Starter #8 (Edited)
And hope you can help with a related question.

The corsair AX1600i says 6+2 PCIe and 4+4 CPU.
The connectors are identical, but I read that the wiring differs between the connections.
So, how do I know which connector is which?

EDIT:

Seem so, the conncectors are identical on the PSU side but differ on the board / GPU side.
Is it right, that I can take any port on the PSU for both cables but assure that I put the right one on the board / GPU?
 

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Correct there as well.
 

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Discussion Starter #10
@oreonutz

yep, I also noticed manuals are a bit sparse; not only with respect to power supply but more in general. I get the impression building a PC - especially with watercooling - is considered a dark art that should not be documented to mere mortals. Good that there is this forum with experienced magicians who are so kind to help :)
 

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noob with threadripper and dual 2080ti and a quadro card, hmmmmmmmmmmmmm
 

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noob with threadripper and dual 2080ti and a quadro card, hmmmmmmmmmmmmm
Hey man, we all got to start somewhere, I envy him for starting there, nobody can say he didn't do his research!
 

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And hope you can help with a related question.

The corsair AX1600i says 6+2 PCIe and 4+4 CPU.
The connectors are identical, but I read that the wiring differs between the connections.
So, how do I know which connector is which?

EDIT:

Seem so, the conncectors are identical on the PSU side but differ on the board / GPU side.
Is it right, that I can take any port on the PSU for both cables but assure that I put the right one on the board / GPU?
Sorry I went to bed after my last message, just now seeing this. Usually corsair labels the Cables on the PSU Side, and they should have given you enough, usually they give you 2 or more EPS, and 4 or More PCIE, and on the side of the cable that plugs into the PSU it should say either CPU/EPS or PCIE. Because Manufactures all have different standards as far as their Pinout on PSU Side, I always make sure to use the correct cables for the correct job, and unless the AX1600i is different from the AX1000i, the cables should be labeled so there would be no need to mix them up. Let me know if they aren't. I would have to lookup the Pinout of both connectors to know for sure if there would or wouldn't be a problem if you plugged say an EPS Cable into a PCIE Slot, then used that cable on a Graphics card, because of the change in PinOut PSU Side, it might actually be a bad thing to do (But would need to investigate further to know for sure)
 

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Discussion Starter #14 (Edited)
@oreonutz

Yep, found out that it's easy with the Corsair cables. I just needed to understand that the side labled with CPU or GPU goes into the socket on the board, not the PSU. On the PSU side they are identical.

Asked here because I am fighting with so much stuff at the same time (what RGB cable goes where (3 pin, 4 pin, 5 v, 12 v), how much total current draw if I splitter fans together, what the heck is that cable that comes out of the case and does not have a lable?).

@dajez
Valid remark.
I am really a noob in building this machine but not in using machines like this. Current one is a Dual Xeon (8 cores each) DELL workstation that is doing my rendering for me for 7 years now. Unfortunately it does not have a working USB 3.0 anymore because no compatible Windows driver for the good ole Renesas controller. And I think, this machine will start to break in the foreseeable future (and mem speed is only 1600mhz).
And it sounds like an army of house maids starting their vacuum cleaners all at the same time (this DELL is a really a hell of loud under load).
So far rendering was mainly CPU based (no need for CUDA or RTX). But with Iray, Cycles, Eevee, Redshift, and even Marvelous Designer now based on or supporting GPU it was time to spend the money saved over the years (Iray and Cycles now have initial RTX support which leads to serious speed boosts). The Quadro card is because of the GL optimized drivers, the GL 10bit output and to keep the UI usable even if the 2080 is under heavy load in interactive mode. Second 2080 TI will either come later or, if the 2080 TI Super rumors are true, I consider getting that one (just fear the GPU block will not fit that).

Yes, I did a lot of research - but as always, doing theoretical reading and in the end fighting with all those real parts and cables is a different thing :)
 

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@oreonutz

Yep, found out that it's easy with the Corsair cables. I just needed to understand that the side labled with CPU or GPU goes into the socket on the board, not the PSU. On the PSU side they are identical.

Asked here because I am fighting with so much stuff at the same time (what RGB cable goes where (3 pin, 4 pin, 5 v, 12 v), how much total current draw if I splitter fans together, what the heck is that cable that comes out of the case and does not have a lable?).

@dajez
Valid remark.
I am really a noob in building this machine but not in using machines like this. Current one is a Dual Xeon (8 cores each) DELL workstation that is doing my rendering for me for 7 years now. Unfortunately it does not have a working USB 3.0 anymore because no compatible Windows driver for the good ole Renesas controller. And I think, this machine will start to break in the foreseeable future (and mem speed is only 1600mhz).
And it sounds like an army of house maids starting their vacuum cleaners all at the same time (this DELL is a really a hell of loud under load).
So far rendering was mainly CPU based (no need for CUDA or RTX). But with Iray, Cycles, Eevee, Redshift, and even Marvelous Designer now based on or supporting GPU it was time to spend the money saved over the years (Iray and Cycles now have initial RTX support which leads to serious speed boosts). The Quadro card is because of the GL optimized drivers, the GL 10bit output and to keep the UI usable even if the 2080 is under heavy load in interactive mode. Second 2080 TI will either come later or, if the 2080 TI Super rumors are true, I consider getting that one (just fear the GPU block will not fit that).

Yes, I did a lot of research - but as always, doing theoretical reading and in the end fighting with all those real parts and cables is a different thing :)
So it is DEFINITELY possible to get your Renesas USB 3 Controller working with Windows 10. I know for sure because I have a Renesas USB3 Card in My PC and use it damn near every day.

And Usually the Side Labeled CPU or GPU goes into the PSU not the actual component. Yours could be different, but I use pretty much only Corsair and EVGA Power Supplies in all my builds, and typically the label side plugs into the PSU, the unlabeled side goes into your components.
 

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Discussion Starter #16
Hm,

the cpu labled side won't fit into the PSU because the clip is to wide.
And the PCIe labled side seems to be the one for the GPU because it can be used as 6 or 8 pin one.
Maybe Corsair changed the labeling?
 

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The CPU labelled side goes to the CPU power socket, not the PSU.

Yes, the PCI-E labelled side plugs into the GPU.

Just check both ends of each cable. It will tell you which end goes where.

Hope this helps.
 

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Discussion Starter #18
That's my conclusion as well. Maybe different models of the PSUs use different labeling.
@oreonutz
I tried to find a driver for the Renesas controller and used all tricks and cheats - no chance. It is just to old. For most newer cards / chips there are some available. So, I am unlucky here (but had another reason to get a new PC).
 

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That's my conclusion as well. Maybe different models of the PSUs use different labeling.

@oreonutz
I tried to find a driver for the Renesas controller and used all tricks and cheats - no chance. It is just to old. For most newer cards / chips there are some available. So, I am unlucky here (but had another reason to get a new PC).
My bad about the cables. The Side where the cables split apart are indeed the side that goes into the device. I obviously was confused about which side the labeling is on, so my bad there.

As far as the driver, give me a few minutes, let me dig one up for you. You are using Windows 10 64 Bit Correct?
 

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That's my conclusion as well. Maybe different models of the PSUs use different labeling.

@oreonutz
I tried to find a driver for the Renesas controller and used all tricks and cheats - no chance. It is just to old. For most newer cards / chips there are some available. So, I am unlucky here (but had another reason to get a new PC).
OK, this driver package should work for you sir. Let me know how it works for you. I have a few different USB PCIE Cards that use the Renesas Controller, and this set of driver works for all of them, so hopefully whatever card you are rocking, these will work for you to. If I remember correctly, after you install you need to reboot. Then You should be good to go! Still obviously build you new PC, but hopefully in the mean time this can get you your USB3 Back!

https://drive.google.com/file/d/19VLSIgelSeXO-1CByLrXFE0TG0ju7RJR/view?usp=sharing
 
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