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Topic: Connecting GPU's with and w/o Risers (Read 293 times)

full member
Activity: 1275
Merit: 141
February 09, 2021, 02:28:56 PM
#26
2 or even 3 psu is no big deal.

mobo all power from same psu
any gpus plugged directly into mobo all on same psu as mobo

any gpu on a riser should get all power to gpu and riser from same psu.....dont mix streams..

sync your psus either through 24pin Y or W cables or through mini 4pin if using server psus and breakout board.

And again respect the wattage limits for chains and connectors off psus.
hero member
Activity: 789
Merit: 501
February 08, 2021, 02:27:54 PM
#25
Technically, 2 PSU will probably be safer.
Because you will have a lot of connector and you will be able to balanced the power on each cable
newbie
Activity: 25
Merit: 0
February 08, 2021, 11:05:30 AM
#24
I don't like the idea of using two power supply in a single mining rig, I'd rather go with big power supply or split the graphic cards and build two mining rigs instead of one, I just feel like it's more safer this way than using two power supply

Besides the phase issue, what else don't you like when using 2 psu's?
member
Activity: 196
Merit: 15
Sovryn - Brings DeFi to Bitcoin
February 08, 2021, 10:08:28 AM
#23
I don't like the idea of using two power supply in a single mining rig, I'd rather go with big power supply or split the graphic cards and build two mining rigs instead of one, I just feel like it's more safer this way than using two power supply
newbie
Activity: 25
Merit: 0
February 08, 2021, 09:25:12 AM
#22
This might be a dumb question but...any issues connecting some GPU's directly on the motherboard and some using risers?

Most mining rigs I see in the internet either have all their gpu's connected on the motherboard or all via risers.

I'm planning to use Asus Z370-E for my rig.

You have to understand how a GPU is powered.
Some power come from the PCI-E slot (75W max on PCI-E 16x slot) and some power come from the 6/8 pins PCI-E connector(s) of the GPU.

The motherboard is compatible with SLI/Crossfire, so at least using 2 PCI-E slots directly is totally fine. Because it's design to give power simulteously to 2 GPU from the PCI-E slots.
If you want to use more GPU, you have to use powered risers (like USB risers) so the power draw that the GPU expect from the slot will not come through the motherboard (and it's a good thing, because it will not be able to safely provide so much power to 4-6 GPU on the slots).
The power will come from the risers with the molex or sata power cable directly from the PSU.

Do not use to much risers on 1 PSU cable.
For exemple, if you have 1 SATA cable from the PSU with 5 SATA plugs ... do not plug 5 risers, be cause it could stress this cable.
I prefer to have max 2 risers per cable on the PSU

Okay I see. I will have two separate 850w PSU's to power eight 3070. I'll make sure to distribute powering the risers between the two psu's. Thanks!


If you are planning to power 8x RTX3070 it will be wiser to buy power supplies with 1200watt capability because a single RTX3070 draws up to 117-120watts per gpu now do the math, that's 960 watts and motherboard and CPU will need some power too

I got two 850w psu's for a total of 1750w. That should be enough?
member
Activity: 238
Merit: 17
Sovryn - Brings DeFi to Bitcoin
February 08, 2021, 09:18:34 AM
#21
If you aren't using a motherboard that have enough space for up to 6 PCIe x16 slots it's better to buy risers to connect your graphic cards, I'm talking about motherboards like in the picture below, if this is what you own then you have no need to buy risers




With this motherboard I can fix up to 4 graphics card without need for risers as there will be good air flow between the cards
newbie
Activity: 25
Merit: 0
February 08, 2021, 08:42:00 AM
#20
Hey,

if you are using dual power supplies do the following :
connect one GPU and its riser to power supply A until you have no more free slots.

Then go to power supply B , and connect each GPU and IT'S Riser to the same PSU!

Do not connect GPU_1 to PSU A and the riser of GPU_1 to PSU 2. Hope it's clear Cheesy

Got it thanks!
newbie
Activity: 25
Merit: 0
February 08, 2021, 08:30:56 AM
#19
If you choose to use 2 PSU's then you need to make damn good and sure that you select a single PSU to power up both the riser and GPU. DO NOT mix the power sources on risers and GPU's or you can cause damage to your equipment and possibly start a fire!

So true ! Smiley
https://www.thegeekpub.com/11955/using-dual-power-supplies-mining/

The key is :
Everything you plug on the MB comes from one PSU (24 pin, CPU pin, molex etc ...)
Everything you plug for a GPU comes from one PSU (Riser power + 6/8 pins PCI-E connector to GPU)

So you will not mix the ground of the 2 PSU and everything will be fine  Smiley

Very useful article thank you! I was not aware that you couldn't mix and match psu connection with the GPU and mobo.

So basically I'll use the first psu for the mobo and 4 GPU/Risers. Then use the second psu isolated on the other 4 GPU/Riser pairs. This should be ok?
member
Activity: 443
Merit: 13
February 08, 2021, 08:30:02 AM
#18
Also, check this diagram here :
https://3.bp.blogspot.com/-Yc7foXYMC58/WmUmqYWR_MI/AAAAAAAAAUk/dl5jRq-YLBUnmQj3JFCuxh5EFjRIj-r6gCLcBGAs/s1600/powerrig.png

A more clear representation of what I wanted to say with my post above.
member
Activity: 443
Merit: 13
February 08, 2021, 08:28:28 AM
#17
Hey,

if you are using dual power supplies do the following :
connect one GPU and its riser to power supply A until you have no more free slots.

Then go to power supply B , and connect each GPU and IT'S Riser to the same PSU!

Do not connect GPU_1 to PSU A and the riser of GPU_1 to PSU 2. Hope it's clear Cheesy
newbie
Activity: 25
Merit: 0
February 08, 2021, 08:21:42 AM
#16
This might be a dumb question but...any issues connecting some GPU's directly on the motherboard and some using risers?

Most mining rigs I see in the internet either have all their gpu's connected on the motherboard or all via risers.

I'm planning to use Asus Z370-E for my rig.

You have to understand how a GPU is powered.
Some power come from the PCI-E slot (75W max on PCI-E 16x slot) and some power come from the 6/8 pins PCI-E connector(s) of the GPU.

The motherboard is compatible with SLI/Crossfire, so at least using 2 PCI-E slots directly is totally fine. Because it's design to give power simulteously to 2 GPU from the PCI-E slots.
If you want to use more GPU, you have to use powered risers (like USB risers) so the power draw that the GPU expect from the slot will not come through the motherboard (and it's a good thing, because it will not be able to safely provide so much power to 4-6 GPU on the slots).
The power will come from the risers with the molex or sata power cable directly from the PSU.

Do not use to much risers on 1 PSU cable.
For exemple, if you have 1 SATA cable from the PSU with 5 SATA plugs ... do not plug 5 risers, be cause it could stress this cable.
I prefer to have max 2 risers per cable on the PSU

Okay I see. I will have two separate 850w PSU's to power eight 3070. I'll make sure to distribute powering the risers between the two psu's. Thanks!



If you choose to use 2 PSU's then you need to make damn good and sure that you select a single PSU to power up both the riser and GPU. DO NOT mix the power sources on risers and GPU's or you can cause damage to your equipment and possibly start a fire!

Do you mean I need to make sure to connect each GPU/Riser pair on the same PSU each? For example, connect GPU/Riser 1-4 pairs on first PSU and connect GPU/Riser 5-8 pairs on second PSU?
member
Activity: 1201
Merit: 26
February 08, 2021, 07:16:50 AM
#15
im not sure how many pci lanes that mobo will support, you can try and see. if after some gpus you will not see in device manager then you are run out pci lanes because when you plug directly to 16x you will loose lanes. my msi x79 no problem 1 gpu plugged to 16x rest 3 out with risers.
hero member
Activity: 789
Merit: 501
February 08, 2021, 05:09:17 AM
#14
If you choose to use 2 PSU's then you need to make damn good and sure that you select a single PSU to power up both the riser and GPU. DO NOT mix the power sources on risers and GPU's or you can cause damage to your equipment and possibly start a fire!

So true ! Smiley
https://www.thegeekpub.com/11955/using-dual-power-supplies-mining/

The key is :
Everything you plug on the MB comes from one PSU (24 pin, CPU pin, molex etc ...)
Everything you plug for a GPU comes from one PSU (Riser power + 6/8 pins PCI-E connector to GPU)

So you will not mix the ground of the 2 PSU and everything will be fine  Smiley
legendary
Activity: 1764
Merit: 1002
February 08, 2021, 03:04:32 AM
#13
This might be a dumb question but...any issues connecting some GPU's directly on the motherboard and some using risers?

Most mining rigs I see in the internet either have all their gpu's connected on the motherboard or all via risers.

I'm planning to use Asus Z370-E for my rig.
only heat the issue but if youre running on water cooled grapics it will be more stable gpu direct on pcie mobo, there is 7 / 8 full pcie mobo and put all together with small  case and only gpu blower fan will do the trick, or all liquid cooler will be nice for looking and silent with lower gpu consumption just for hobbies
hero member
Activity: 2548
Merit: 769
February 08, 2021, 01:18:27 AM
#12
I used motherboard PCI-e without risers only in 2 choices: it was test rig for 1-2 GPUs and I mistaked and had not enough risers but had reserve PSUs and motherboards.
It will work fine but it will not be easy to construct normal rig with different GPU connection.
member
Activity: 504
Merit: 16
February 08, 2021, 12:31:51 AM
#11
It makes more sense to use risers for all the graphic cards to get better cooling, if you insert a card into the 1st pcie slot and use riser on others there will be heat because a card is underneath doing a hardwork too, user risers and create space between the gpus
full member
Activity: 952
Merit: 110
February 08, 2021, 12:22:39 AM
#10
This might be a dumb question but...any issues connecting some GPU's directly on the motherboard and some using risers?

Most mining rigs I see in the internet either have all their gpu's connected on the motherboard or all via risers.

I'm planning to use Asus Z370-E for my rig.

You have to understand how a GPU is powered.
Some power come from the PCI-E slot (75W max on PCI-E 16x slot) and some power come from the 6/8 pins PCI-E connector(s) of the GPU.

The motherboard is compatible with SLI/Crossfire, so at least using 2 PCI-E slots directly is totally fine. Because it's design to give power simulteously to 2 GPU from the PCI-E slots.
If you want to use more GPU, you have to use powered risers (like USB risers) so the power draw that the GPU expect from the slot will not come through the motherboard (and it's a good thing, because it will not be able to safely provide so much power to 4-6 GPU on the slots).
The power will come from the risers with the molex or sata power cable directly from the PSU.

Do not use to much risers on 1 PSU cable.
For exemple, if you have 1 SATA cable from the PSU with 5 SATA plugs ... do not plug 5 risers, be cause it could stress this cable.
I prefer to have max 2 risers per cable on the PSU

Okay I see. I will have two separate 850w PSU's to power eight 3070. I'll make sure to distribute powering the risers between the two psu's. Thanks!


If you are planning to power 8x RTX3070 it will be wiser to buy power supplies with 1200watt capability because a single RTX3070 draws up to 117-120watts per gpu now do the math, that's 960 watts and motherboard and CPU will need some power too
sr. member
Activity: 756
Merit: 251
Sovryn - 300-500% APY on USDT Deposit
February 07, 2021, 09:03:15 PM
#9
Are you going to mine inside a case? because usually the one that want to connect 2 GPU directly to the motherboard doen't use open case. It's okay but the temperature will be higher than using riser because you will space them properly. You'll probably run into thermal throttle if you are planning to use 3080 / 3090 but other than that i think it will be okay. I've seen someone open the side panel and using 1 riser for the 2nd gpu.
full member
Activity: 1424
Merit: 225
February 07, 2021, 08:27:07 PM
#8
Newbie should avoid multi-PSU, keep it simple to start.
Regarding the initial question, connecting 2 GPUs directly to the motherboard is
fine if the x16 slots are properly spaced. It will run a little hotter but saves one
extra power connection. There is some good discussion in recent threads about how
to power risers. TLDR: SATA is bad.
full member
Activity: 626
Merit: 159
February 07, 2021, 07:42:53 PM
#7
This might be a dumb question but...any issues connecting some GPU's directly on the motherboard and some using risers?

Most mining rigs I see in the internet either have all their gpu's connected on the motherboard or all via risers.

I'm planning to use Asus Z370-E for my rig.

You have to understand how a GPU is powered.
Some power come from the PCI-E slot (75W max on PCI-E 16x slot) and some power come from the 6/8 pins PCI-E connector(s) of the GPU.

The motherboard is compatible with SLI/Crossfire, so at least using 2 PCI-E slots directly is totally fine. Because it's design to give power simulteously to 2 GPU from the PCI-E slots.
If you want to use more GPU, you have to use powered risers (like USB risers) so the power draw that the GPU expect from the slot will not come through the motherboard (and it's a good thing, because it will not be able to safely provide so much power to 4-6 GPU on the slots).
The power will come from the risers with the molex or sata power cable directly from the PSU.

Do not use to much risers on 1 PSU cable.
For exemple, if you have 1 SATA cable from the PSU with 5 SATA plugs ... do not plug 5 risers, be cause it could stress this cable.
I prefer to have max 2 risers per cable on the PSU

Okay I see. I will have two separate 850w PSU's to power eight 3070. I'll make sure to distribute powering the risers between the two psu's. Thanks!



If you choose to use 2 PSU's then you need to make damn good and sure that you select a single PSU to power up both the riser and GPU. DO NOT mix the power sources on risers and GPU's or you can cause damage to your equipment and possibly start a fire!
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