Topic: molex to pwoer the risers (Read 279 times)

Yes generally the weak-point is the cheap SATA connector on the riser. Its badly built and its what usually ends up melting first. In my opinion when they include these SATA connectors and knowing that people will pull more than 50Watts from it, they should at least make it more robust. I think the issue is that its not a tight connection as a retail SSD or HDD. Those are usually hard to connect and disconnect.

The SATA connector to risers is not as tight and you can feel that there is a small gap which will lead to a bad connection and obviously something end up melting. Even if the connector was good I would just avoid using the SATA connection all together. Molex or PCIe is much safer and don't need toworry about anything.

Ther issue with SATA power is the connector. You can get 2xSATA to 6 pin PCIe adapters to solve that issue.
Most are actually 6+2 but I would only use 6.

You can also use the weakest solution on the riser for the GPU that will draw the least power, based on the
card's TDP and the number of power connections.

For example I have an EVGA 1070 FTW that is rated at 150W with 8+8 power connections. Including the riser
that's 425W of supply for 150W of draw. The riser can be expected to draw around 30W and the 8 pin PCIe
around 60W each. Even a SATA riser can handle that.

That's an extreme example but anything below 50W is safe for one SATA connector.

ok i see...

what about sticking to molex cables at least for the risers ??!...

thanks,

windows 10 for me

what is a runaway wattage i didnt quite get that ?!?...

i got 4x 3060 Ti single 6 pin and one 3070 Ti with dual 8pin (all zotac)
i also have a 1080 Ti...

The 3060 Ti I have reduced the pwoer target to 130w only ! shouldnt i be safe ?!

i was refering to the original modular Molex cables from the PSU not cheap 3$ stuff,,,

and yes ill only use the splitters for the risers not really for any GPUs those can run with dedicated pci cables from the PSU...

I understand,

So under Windows you dont recommend using sata cables at all?

And they may never go off settings and max to 190-210 or they may do it tomorrow.

I can go weeks without the issue or it can happen tonight.

Every generation of nvidia or amd since I first used an old amd in my 2010 mac pro to run gou mining for bitcoin in 2012 has had dropping of settings and gone to full power.

the amd 5770 the amd 6790 the  7950 the r 280 the 470 the 570 the vega the 5700

not my lone 6800xt as it has been always on smos.

my gtx 970 1070 2070 3070 3080 all have dropped out and gone to max tdp.

I have used maybe 450 different gpus.since 2012.

and if you miss it and let it run a long time at full speed and full power it melts riser cables

Hi philipma1957,

I have 30x3070 and all of them are bellow 130w on windows 10. At least thats what miner (TREX) is showing.

Here goes nothing. All answers are ignoring a really important piece of information.

what is your os?

windows often allows settings for gpu to drop.

Thus the card draws max.

I have 2 pcs that have a card that run windows 10 and use msi afterburner.

Both of these cards go run away and pull 190 to 215 watts.

So if you run windows with risers powered by sata and or molex they can burn 🔥 melt the cables.

If you run linux I run smos run away wattage almost never happens.

that means using two risers on your molex cables and 1 riser on your sata cables should be safe.

That psu has two molex cables and 2 sata cables so in theory you could attach up to six risers safely if you use smos or hiveos a linux os.

next problem is what are your cards.

I have a stud 3060ti it is the aorus and can pull 215 watts.
It has two eight pin jacks.

I have two evga 3060 ti they can only pull 190 watts.

I have three 3070

one pulls 195 watts
one pulls 200 watts
one puls 210 watts

note all cards above are when runaway wattage happens.

all cards above did this on windows 10
along with my evga 3080 cards

none have done run away on my smos setups.

makes it hard for me to tell you
a single sata cable is safe for one riser
a  molex cable is safe for for two risers.

the reality is for 3060ti and 3070 they should be safe if you set power to 130 watts on a linux os.
and on a windows 10 they are not as safe no matter how you set you clocks since on windows clocks drop out.
 

Power draw depends entirely on the graphics card and there are many that pull more than the specified 75W. But I don't know if risers that use e.g. USB cables actually do deliver 75W over the USB cable. I always was under the impression that modern risers don't take power from the motherboard at all and use their power connector to deliver power to the GPU. BUt I might be wrong, a clarification on that question would be nice.
Molex-4-pin is safe if it's a well built adapter that uses original Molex connectors and thick enough cables. I wouldn't use flimsy 3$-adapters from China indeed.

I don't like these splitters as the 6-pin connector is designed for 150W and the 8-pin connectors are designed for 225W. So theoretically you could send 450W via a connector that is rated at only 150W. Bear that in mind. Should be fine for powering the risers but don't connect powerhungry GPUs to those splitters.

now am hearing contradicting info ! as per wikipedia molex can supply up to 130~ w from the PSU, thats more than enough for the risers pulling 75w only, am i missing something ?!?!

i also did buy these just not sure what wattage they can handle, should i return them back ?!?...
https://www.amazon.ae/gp/product/B08YCX59QV/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

thanks,

i hope ur right ! probably gonna stick to one molex per riser, its more than enough tbh...

thanks,

the riser only consume around 15watt or less, and dont use molex to pcie, it will burn your cable, better to buy pcie spliter can handle up to 150w for safe long term use, or buying other pcie cable

See https://en.wikipedia.org/wiki/Molex_connector
That's 132W and the cables get 30°C hotter. Two risers pulling 75W each would push it. If you feel lucky, go ahead, if you wanna be safe, get a different PSU. Some cards pull more than 75W from the slot. 

No !

How many risers do u run per single molex cable ?...
I got one psu only per rig so won't mix anything...

Thx

If you can ... DO NOT USE SATA adapter.
SATA can't pull more than 45-50W and the PCI-E Slot can ask for 75W at max.

So if you can, use PCI-E 6 pin connector ... if you can't use MOLEX ... if you can't use SATA but you have to know what you are doing (check the power consumption of the PCI-E slot)

Excellent link to understand the cable management : https://www.gpuminingresources.com/p/psu-cables.html

I am worried now!
Any more opinions?

ehh, I use those, sata to pcie on 3 gpus and it is fine. if they cant hadle ~50W than fuckem.

Many horror stories about those...

What about sata to 6 pin, which comes with many risers.


Is this safe/ok to use?

I use molex to power the risers and PCIE to power cards.  Never had an issue.  Of course, don't mix  the power supplies to the same card/riser

The 75W are used by the card as the power is provided by the PCI-E slot to the card. Early risers were not powered and delivered power straight from the PCI-E slot on the mainboard to the graphics card, which sometimes led to problems. The 4-pin Molex connectors are not rated for 75W so it would be advisable to keep using the PCI-E cables. Actually it can deliver 132W if it's a quality connector and not some cheap china shit: https://en.wikipedia.org/wiki/Molex_connector
I recommend to buy a used server power supply and a breakout board + additional PCI-E cables. See https://www.parallelminer.com/product/x11-breakout-board-with-pcie-power-cables-for-gpu-asic-mining-compatible-with-delta-oems-750w-1200w-1400w-1500w-2400watt-power-supply-more/ for example, the compatible power supplies can be bought used for very little money compared to standard ATX PSUs.

hi

i bought this PSU
https://www.anandtech.com/show/10820/the-zalman-zm1200-ebt-1200w-psu-review/2

and it seems to run fine except the notorious issue of not having enough cables with many PSUs, i got 6x PCI cables and that was enough to run 2x 3060 ti and one dual pin 3070 and two risers !

i was thinking of using the molex cable since i got plenty to run the risers, my understanding risers use 75w ? is that consumed by the card or the riser itself could it go more or less ??!??

what about using the molex cables isntead of PCI-E cables ??

i need a definitive asnwer regarding this please not just speculations !...

and of course am not gonna touch the sata cables !...

thanks,