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What power connections do I need?

J

Jriker1

Joined
Aug 10, 2013
Messages
19 (0.00/day)
I am looking to build a new system and the amount of power connections I am seeing needed for this build is causing me to scratch my head. What I'm looking to get:

1. Asus TRX40-XE
2. Threadripper CPU 3960X
3. NVidia RTX 3090 Founders Edition

So the main thing I'm concerned about is the 8-pin requirements. The Asus Motherboard has 2 8-pin power connections on it. So does the NVidia or it has shall I say two 8 pin to 1 mini 12 pin connector.

I see power supplies with like

2 x 8 Pin EPS / ATX 12V connector (”500mm” x 2)
1 x 4-Pin EPS / ATX 12V connector (500mm)
2 x 6-Pin PCIE connector (”500mm” x 2)

So now we get EPS/ATX connectors and PCIE connectors. Which are you supposed to use where and how would I wire up the motherboard and the GPU in this case? Assuming this PSU doesn't have the right connections but thought I'd ask.

Thanks.

JR
 
The 8 pin power connector for the main board and 8 pin for the video card are different. They can't be used interchangeably.

The 8 pin for the main board can be called CPU or EPS. Also, 4 of the pins can usually be split off to create a 4 pin CPU connector (some main board use this (or used to use it)). Most main board use only one CPU 8 pin.

The 8 pin for the GPU is called PCIe. Again, 2 of the pins can be usually split off to create a 6 pin PCIe connector (some video cards have 6 pin PCIe connectors).

That PSU probably does not have the right connections because it only has two 6 pin PCIe. Not sure what kind of PSU it is, since all the good ones sold now have 8 pin PCIe connecors.

You should probably get a PSU that has enough CPU 8 pins for your system (I guess that is 2) and enough PCIe 8 pins (I guess that is 2 as well). I never used a main board that has more than one CPU 8 pin, so I'm not exactly sure what the exact requirements for such a main board are. Check the manual for exact information on how many CPU 8 pins you need and if they are optional.
 
Thanks for the reply. I've used many a board with two but you only ever needed one. The manual, unless I'm missing it doesn't say. And ready for a shocker? Asus didn't reply to my support email. The power supplies are basically server power supplies because I'm using a 2U enclosure (no comments hehe). Even the SilverStone unit

SilverStone GM1000-2UG INTRODUCTION (silverstonetek.com)

Only has 6 pin for some reason. I hear the other two pins are ground but converting them from 6 -> 8 isn't recommended due to ground loop problems so not sure how hard it is for the manufacturer to make those additional pins available.
 
I see. I'm not familiar with server power supplies or rack mount cases. I guess power supplies meant for rack mount cases may not often have the connectors needed for desktop video cards. Can a large video card like RTX 3090 really fit into a 2U rack mount case?
 
Yep, if you do it horizontally. Or I'm going to give it a try. :)

I know there used to be but has been a while since I built a new system, a way to take like sata connectors or some other connectors and convert them but not sure what that would be.

Maybe something like this?

1612564880991.png


Or I found this from Athena Power. I'm assume EPS power is a lot more than PCIE? Converts an 8-pin EPS power to two 8-pin PCI-E? Assuming I will not be using the second one on the MB?

1612565065273.png
 
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I'm not entirely familiar with TRX40 power requirements but I wouldnt risk a potential underpower of the 280~290W (stock) 3960X or the board itself by connecting only one 8-pin EPS at it.
The 3090FE is designed to work with 2x6-pin PCI-E on its 12-pin adaptor. With a card TBP power limit of 350W and the 375W power availability of the connectors (2x150W + 75W from slot) is all you need as long as the PSU can deliver the 2x150W from the 2x6-pin.
 
Thanks or the reply. First I've been able to find anyone who felt both 8-pin EPS connections should be powered on the MB. No one can ever answer that. That said, the 3090FE looks like it comes with a 2 8-pin PCIE power to 12 not 6. If it was 6 wouldn't be an issue. I have 2 6-pin PCIE connectors on my power. Thinking of switching to an 3080FE as I'm not seeing much rendering value for the price difference but still the same dual 8-pin to 12.
 
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OK so if I have

2 x 8 Pin EPS / ATX 12V connector (”500mm” x 2) for the motherboard.

2 x 6-Pin PCIE connectors for the GPU but I need 2 8-pin. So I could in theory convert a 6 to 8 but wouldn't in theory it make sense to have something where you use the 6-pin PCIE and for the other two pins use a molex connector to two pin to add more juice? People say sure use the 6 to 8 pin converter and you should be good. Or use two molex to 8-pin PCIE and should be good but still seeing I have 6-pin PCIE connections and to me makes sense to use that plus additional juice from another source as mentioned like the molex. But never see a converter like that so confused. Thoughts?
 
just a piece of advice. i own a couple 3090FE's & they have moments during heavy rendering, where they draw shy of 500 Watts through those PCI cables. if your Power Supply is not up to snuff, it will trip Over Voltage protection if your PSU has it. For reference, i had a very capable Seasonic Focus+ Gold 750W, & it couldnt take 30 seconds of playing escape from tarkov, before total system shutdown. Wizard did some readings using a wall meter at the , & it showed during certain situations (like 3d rendering) it Sucks power. i hope you dont encounter this, but im saying it in case it happens , or in case you can plan for it, to avoid what i had to go through. its annoying finally getting a 3090, only to have to put it back in a box for a week, while you drop another $250 on a PSU, to replace the perfectly capable PSU you already bought.

the 3090FE has a power cable adapter, which requires 2 8 pin power cables, & its best to run a separate PCI cable for each of those 8pin plugs.
if you like or need it, i can link you a couple which would be sufficient.
 
what is that PSU going in? thats a redundant power supply. is this for a server? also that wouldnt be sufficient for the 3090, you need Two 8pin PCIe cables.

what store do you shop from? link it please

that motherboard will require Two 8pin CPU power cables (not the same plug as PCI)
 
That is not a standard PSU for a desktop.
The question above is relevant to say the least of it, if it's a server you are building a gold rated PSU is almost mandatory for reliability and DO NOT skimp on the quality of the PSU if it is a server you're building.
Here is an example of a typical PSU:
www.newegg.com

Rosewill Hive Series 850W Modular Gaming Power Supply - Newegg.com

Buy Rosewill HIVE Series, HIVE-850S, 850W Fully Modular Power Supply, 80 PLUS BRONZE Certified, Single +12V Rail, SLI & CrossFire Ready, Black with fast shipping and top-rated customer service. Once you know, you Newegg!
www.newegg.com www.newegg.com

I'm not suggesting this one for your build, it's just an example of a typical PSU for desktops.
 
youd want something like this.
CORSAIR RMx Series RM1000X 1000W 80 PLUS GOLD Haswell Ready Full Modular ATX12V & EPS12V Power Supply SLI and Crossfire Ready, CP-9020094-NA - Newegg.com

most connections are standard, but for your motherboard & GPU, you need ot see 2 4+4, or 8pin CPU cables, & atleast two 8pin PCI cables.
it depends on your case, but most often ,you'll want an ATX Power supply. like the one in the link.

if you provide a link to stores that you shop at, i will find a suitable selection for you to pick from
 
Probably got lost in the thread but I'm building a 2U render workstation so right now until I build everything and can see if I can jury rig a ATX PSU in there, assuming I want to find a 2U PSU. Either single or redundant. Oddly the redundant 1U units are more powerful than a single 2U unit. Did I review the one I linked wrong? Thought it was 80 Plus Gold but kind of the point of my challenges here that it has 2 6-pin PCIE connectors.

Edit: Was also considering this one Industrial Chassis | iStarUSA Products | TC-2U80PD8 - 2U 800W High Efficiency Switching Power Supply

Has the connections I need just more difficult to source. Plus it may be to deep.

EDIT: The MB I'm using or plan to is Asus ROG Strix TRX40-XE Gaming
 
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Adapters are typically excellent firestarters, a good PSU will have the correct cabling needed without the risk of fire or at least a plugin meltdown.
It happens - I can personally vouch for that since I melted such an adapter for a fan I was running in my watercooling setup.
 
id suggest against this idea. rigging cables & molex adapters is a bad idea at any time. im not familiar with the world of server/enterprise components enough to offer advice, but id say cutting corners is a bad choice. you can build a render workstation in a traditional ATX case, or E-ATX case, without going overboard. it will look like a normal PC, but you can call it what you like.

id say, buy a normal ATX/EATX case, put a appropriate PSU in it, & youre off
 
Thanks, I hear you with the case but this is the way it has to be. :) I have an entire server rack in my basement with 2U of space open at the bottom of the case from something else that I took out where I want to fit it in. Hate the concept of building a tower PC and having it sit in the rack sideways or otherwise. I know this is frowned upon but I am working on a pet project to have a 2U water cooled render server and it's going to take me a while to get it all right but am close. The power supply is the main piece I'm struggling with identifying right now.
 
just make sure you have atleast 2x 8pin CPU, & 2x 8pin PCI, the rest is standard. the CPU can also be 4+4Pin (which is 8pin) & the PCI can also be 6+2pin (which is also 8pin) sounds obvious, but many people dont make the connection
 
Jriker1 said:
Thanks, I hear you with the case but this is the way it has to be. :) I have an entire server rack in my basement with 2U of space open at the bottom of the case from something else that I took out where I want to fit it in. Hate the concept of building a tower PC and having it sit in the rack sideways or otherwise. I know this is frowned upon but I am working on a pet project to have a 2U water cooled render server and it's going to take me a while to get it all right but am close. The power supply is the main piece I'm struggling with identifying right now.
Click to expand...
Hi,
Get a atx test bench then.
 
I have one. What if a power supply is like the below? Not sure if I'm reading it right but the part I included looks like it has one 6+2 PCI-E, and 2CPU 8-pin's. But it also has those two 4 pin connectors coming off the CPU. I can't use those as a second PCIE-4 connector can I?

1613948258759.png
 
Jriker1 said:
I have one. What if a power supply is like the below? Not sure if I'm reading it right but the part I included looks like it has one 6+2 PCI-E, and 2CPU 8-pin's. But it also has those two 4 pin connectors coming off the CPU. I can't use those as a second PCIE-4 connector can I?

View attachment 189386
Click to expand...

No you can't - Voltage and so on are different for PCI-E based components.
The only PCI-E connector in that pic is the P4 labeled one.
 
the 3090 requires 2x8pin, or 2x6+2pin PCI cables. those 4pins would just remain unused for your current motherboard, it uses a large amount of CPU power already, through the 2x 8pin CPU.
 
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