I provide a link in my original post that shows a GTX 1080 ti draws 4.4 amps at 80% (measured).
I just checked it out. Based on their measurements, at least based on a founders edition card, I doubt it would draw more than ~4.4-4.5A unless you were running it over 100% power limit, but still I went ahead and ordered some molex risers just to be safe. I suspect the EVGA SC cards would be pretty much in line with the reference cards in terms of power draw, but I’m not sure if this would apply to my zotac cards as they have 2x 8 pin connectors but I have limited them to be drawing around the same power (250W) as the EVGA cards. Still, I might as well move them over to a molex riser. It looks like I should be able to run 2 risers off 1 molex cable (and still be able to deliver more power than individual sata cables). I don’t think I have enough molex cables to run each card individually on a molex cable, I think I have maybe 5 spare molex cables. At the very least I want to run the EVGA cards on molex risers.
I have seen a single XFX RX480 card get a SATA to molex connector very hot to the touch, while two nitro sapphire RX480’s don’t get hot at all. Not that I would normally run two risers on a SATA cable, but I have been testing these crappy connectors to see what I can find. Of the three different types I have, one that gets very hot, I have scanned all with an X-ray micro CT system over the weekend. I am still processing the images but will post the results when I have a chance.
I also plan to do some destructive testing and run 5.5 amps through these connectors and measure the temp… if they don’t burst into flames first.
While clearly not a safe option, I did run my GTX 1070’s and Zotac 1080Ti’s via 1 sata cable powering 2 risers (2 cables across 4 risers) without any issue until I rewired it. I didn’t measure any temperatures but qualitatively the connectors didn’t feel hot. These are Asus Strix 1070’s though which run an 8 pin connector (not sure what reference cards run, although I’m guessing 2x 6 pin which would give the same power anyway…) and zotac 1080Ti’s which have 2x 8 pin (where as standard has an 8 pin + 6 pin). It could be that the 1070’s get enough power from the 8 pin (those cards only sit at ~150W anyway which is about what an 8 pin supplies) and the zotac cards get more than enough power since they have 2x 8 pin (plus I run them at 85% power).
It would be interesting to test the PCI draw from various non reference GPU’s, and maybe this makes cards like zotac amp extremes safer as they are designed to handle more power via 2x 8 pin but can be dialed down to lower % thresholds. When I get the molex risers I’ll probably just use them for the EVGA cards since I don’t have enough molex cables to run all the cards on molex.
A lot of thanks for the explanation and the tools presentation.
Now i have another question:
- Why do the “pro btc” mobo have one or two 4p connector when they are no electrical link between itself and the riser?
- Are the dual sata to 6 pin adaptater any good?
Sorry, been on vacation.
I use OpenHab on a raspberry pi (https://www.openhab.org/), First Alert Zsmoke, and GE ZW4101 modules on my primary PSU’s. You can also use a Smartthings hub in place of OpenHab.
I only do this for the rigs I have in my home. Only a few in summer, but up to 10kW in winter (its free heat). If I only had a pool then I could heat that in the summer too.
deleted for brevity.
Thanks for this. I assumed if you have a 20 amp breaker you are fine as long as you stay below 20 amps. I have a 15 amp breaker am currently using 1300 watts, 11.5 amps. with 7 card rig (and everything else). So the limit would be 12 amps continuous? 
I am planning on adding an 8th card.
Here is concretely how much 2x1080ti and 1x1060 draw current (powerlimits 175W for ti’s and 85W for 1060).
Risers and cards are powered from 12V server power supply.
O.
@ZC93, so your saying that its perfectly ok on an 8 GPU rig to get 2 750w PSUs use one to power the motherboard and using the 4 PCIE connectors to power a GPU( 8 pin) and a riser(6 pin) on a leg using a splitter and with the other PSU power the other PSU to power the remaining GPUs? GPUs I’m thinking of are GTX 1070s. Ive been looking for some solid information on this for a while. Im glad you posted.
Therefore, do NOT use the molex to SATA adapters. Run a 4 pin molex cable from your PSU directly to your riser get rid of the SATA adapter.
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I’m confused. This sounds fine on the surface but how should we connect them? The risers are powered via a 6-pin connector. (Most come with a 6-pin > SATA).
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And just to make sure I’m perfectly clear, you’re saying that using the provided 6-pin > SATA is fine if the 1080 Ti’s are power limited to 80% or lower?
There is a huge variety of risers and how to power them. I just bought, for testing, ver. 008s risers than can be powered by 6-Pin PCIe, 4-Pin MOLEX, or 15-pin SATA. You can use the Sata, but best practice is one cable per riser. Molex you can run two per cable, and 6-pin PCIe two per cable (though what a waste of a VGA slot). Under no circumstances should you use that P.O.S. adapter that connects a a sata cable to a PCIe, unless you want a potential visit from the fire department.
There really isn’t a cost difference in risers, so buy what you believe is the best for you.
You can use Sata @ 100%, just use a single cable
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I feel like with each post I read I’m just getting more and more confused instead of understanding.
What risers do you recommend? I’m buying a 1600W PSU as soon as I can find one for my currently owned 1080Ti’s. Currently have these risers. They had good reviews but now I’m second guessing them?: https://www.amazon.com/gp/product/B074PS39BK/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1
Any feedback would be great.
What are you using? Or what would you use for a 6 GPU rig?
you can use those risers, just without that adapter.
I’ve use/used Ver 007s
and I am testing the these out of P.o.s rig of two gtx 780’s, a gtx 580 and two amd 6970’s Ver 008s
This is not who I purchased them from, just the first link to the riser itself
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Interesting. Looks like those connect directly with the SATA cables. Very nice. I’ve ordered some to try. I will say however that several people in the reviews have complained about them catching fire so I still don’t see the safety issue as resolved.
with version 7 and again only one power cable from psu per riser
Is there any advice on running 2 x psu with 6pin risers? Thanks
those cables are used to power VGA gpu’s, you should have no issues running two 6 pin risers per cable.
Hello and thanks for this very interesting topic !
I have this PSU https://seasonic.com/prime-1300-w-gold and those risers : https://www.amazon.fr/gp/product/B07516Y1P8
My problem is i supply my gpu with 8 pin each (and i have a 6pin unused on each cable). How i can supply my risers ?
Option 1 : I connect the unused 6 pin (from 8 pin psu) to the riser. And the 8 pin will supply the gpu with 8pins and the riser with 6 pin
Option 2 : I supply each riser from the psu with Molex 4pins (but the problem is i don’t have enough cable, i’m waiting seasonic support answer)
Thanks for your help!