Bitcoin Forum

Hi,

I'm going to order 8 or so risers (will only use 6 GPU's but wanted two extra spares just in case) but I'm not quite sure what to pick. I've also got a question for you experienced miners regarding PSU cables for the risers. So here goes.

Should I order risers with 6-pin connectors? If so, can I power 1 GPU and 1 riser with the same cable from the PSU? If not, then the cables on the PSU won't be enough.

Or should I order risers with molex connectors? If so, can I power two risers with one cable from the PSU? Also, the EVGA G2 1300 that I've purchased only have two cables with molex, would it be possible to take another one from my EVGA G2 750 that I'm not using? I'm assuming it's the same cables. Can I plug the third molex cable (on the PSU side) into one of the ones that are supposed to be for the sata cables (there are only two peripheral slots on the PSU)?

Thank you!

This is definitely a tricky question.

The riser cards do pull a fair amount of wattage, so you definitely don't want to string a bunch of them on one line. Also the SATA to MOLEX adapters can melt, so I hear. I've never had it happen, but to be safe, try and not use them.

I only put a max of 2 risers on a chain, and less if possible.

I use a mix of the molex powered adapters and the SATA powered adapters like this:
https://www.amazon.com/CHICPICK-Dedicated-Graphics-Extension-Connector/dp/B01NBIOXNQ

I haven't had any problems yet, but like I mentioned, I only do 2 max per chain, 1 if possible.

If you have extra 6-pin, definitely use those, because they are designed to put out more wattage and are less likely to overheat.

The PSU I've purchased has six dedicated cables for the GPU's, so if I can use each cable for one GPU and one riser, then it's all good and I'll go with that.

If that's not recommended, then I'll have to use the molex's but the PSU only has two dedicated molex cables. So with six risers, I'd need an extra molex cable. Question is if I can plug it into the connector in the PSU that's supposed to be for SATA cables - and if I can take that molex cable from another PSU (same model but lower watt)?

most PSU these days have limited molex connector, and have a tons of sata connector
and most sata cable will be burned out to flame on RX GPU, so there are no place for sata in mining rig to be safe
since pcie 6-pin cables are limited, and even more limited molex, it still better to use pcie 6 pin cables since their spec is designed to deliver up to 150w (molex is only 50w, sata is only 35w)

so the solution is just use PCIE 6-pin splitter, one end for riser, and another one for gpu, so each gpu+riser only use one cable from PSU

https://i.imgur.com/FiSGp0f.jpg

https://i.imgur.com/bT5Pq29.jpg

Is this the cable?

http://www.ebay.com/itm/18AWG-6-pin-to-2x-6-2-pin-6-pin-8-pin-Power-Splitter-Cable-PCIE-PCI-Express-/361651807884?hash=item543420a68c:g:eEYAAOSw0fhXjlMJ

if you want to use multiple PSU,, you shouldn't mix 1 PSU for riser and another for GPU.

GPU+Riser should be powered by same PSU, as there are electrical power connection between PCIE power socket on GPU and PCIE slot in Riser.
Power connector on riser is not to power up riser, it is to power up gpu via pcie-slot 1x connector which spec is allow gpu to take up to 72w from these pcie 1x slot, so sata powered riser is should not be allowed

splitting multiple psu between gpu and mothherboard is fine, splitting multiple psu between (gpu+riser) and another (gpu+riser) is fine too

yup that it is, only use pcie splitter that use at least 18 awg wire, 16 awg is better, but never use 20 or 24awg wire

A fully modular PSU like Corsair RM1000i comes directly with 8 PCIE cables that can be made 6 or 8 pin and it can support up to 8 GPU-s , it also come with 12 Sata cable connectors enough to power up many risers. I think the PSU is the most delicate part choosing when building a mining rig. This PSU supports easily up to 6 cards of RX 480,tested by me as one card max power draw I see in GPU-z latest version is 133 watt.

http://www.corsair.com/en-gb/rmi-series-rm1000i-1000-watt-80-plus-gold-certified-fully-modular-psu (http://www.corsair.com/en-gb/rmi-series-rm1000i-1000-watt-80-plus-gold-certified-fully-modular-psu)

RX480 is powered by 6-pin pcie power not 8-pin so it definitely take up to 75w from the connector (since 6-pin pcie is max 75w, 25w for each pin), if the gpu take 133w then there are 133-75 = 58w gpu take from PCIE slot 1X, i am sure it is only for peak consumption of short period of time, it its continuously like this then sata power connector will be burn because sata only limited to 35w power delivery

so never use any sata power for gpu mining

RX 480 is powered up by 8-pin pcie power and not 6-pin, I have it right in front of me so I am not wrong. The sata is only connected to the riser from the PSU and the card also get's power from the PSU via the 8-pin pcie cable. I have those running from a few weeks and I don't see any problem until now.

Sorry if I wasn't clear with my message. I'll try to explain what I meant better.

The EVGA G2 1300 that I've purchased is modular and has two inputs for molex cables. Which means I could maybe run two risers per cable for a total of four risers.

However, the PSU also has inputs that are meant for SATA cables. The connector looks the same. Could I take one of the molex cables that came with my other EVGA G2 750 that I don't use and plug it into one of the SATA connectors on the 1300 PSU?

If you look at this image it might be clearer what I mean. The molex connectors are the ones called "PERF1" and "PERF2". To the left of those there are four connectors for SATA cables. Could I use another molex cable and plug it in to the SATA connectors instead?

https://www.evga.com/products/images/gallery/120-G2-1300-XR_XL_5.jpg

yes you can, personally i have EVGA GQ series exactly like that, and done cable test using multimeter
if G2 and GQ are same then you can put sata/molex to that connector like i did, but i never had G2

@Uray

I just checked to make sure if it some overheating was happening as after reading what you told me I just got to check the cards on the riser. Normal heat, just like the one in the motherboard. Sata 4 pin cable is ok  too. I hope I will not burn anything by keeping this configuration but I have seen many mining videos on youtube that are on this exact configuration as mine.

That's great news if it's possible!

This also means that I should buy risers with molex connectors, I assume? That way I don't need to buy extra 6-pin splitters. Or is 6-pin splitters and use them still better than using molex cables?

Edit: I should mention that I've purchased six Sappphire RX 570 Pulse Mini. According to Sapphire they're drawing less than 150W. If the 6-pin cable is rated for 150W then molex with another 50W should be more than enough for those GPU's, correct?

Hi all,
sorry for the silly wuestion, but of course I lack in knowledge of hardware, since I can't understand this point.
You said that every card+raiser need power supply, and you use PCIE 6-pin splitter for every card, so you have a total of 6 PCIE 6-pin cables. But if the connectors are only 2 in the PSU (in the picture OP posted I presume they are perif1 and 2, as he said), how do you connect them?
I know it is a dumb question, but I can't figure it out.
Thanks

The molex cables are connected to the "PERIF1" and "PERIF2". It looks like 6-pins on the PSU but the other end of the "PERIF1" and "PERIF2" are molex cables.

The 6-pin cables that we're talking about are the ones that are used on GPU's. On the PSU they are connected to the ones on the right (the VGA1-6). So there are 6x 6-pin cables. Molex cables, however, only have two connectors on the PSU (the "PERIF1" and "PERIF2").

He was talking about splitting those 6 cables to make them 12 in order to use them for both the GPU's and risers.

I hope that makes more sense.

one dedicated molex cable for one riser is safe, but never use single cable for multiple riser in daisy chain

but personally i prefer to use 6-pin powered riser, not just because its safer, but molex powered riser are using 1x 12v (yellow) and 1x 5v (red) rail.
while pcie riser use 3x 12v (yellow) rail
most psu has limited 5v rail wattage, but huge 12v wattage (and mostly psu watt spec are for 12v rail, so 1000w psu means 1000w for 12v rail). if you ran out of 5v watt limit it could be problematic

GPU use 12v and 5v to power up, most 12v are taken from GPU power connector, and 5v (and some tiny 12v) are taken from PCIE-1X slot
on PCIE 6-pin powered riser it mising 5v pin, they convert 12v to 5v by using step down converter, highlighted in red box, so these riser only take 12v and convert some into 5v, so it does not use 5v rail from PSU, while Molex riser directly use 12v and 5v from PSU without any conversion

https://i.imgur.com/BpOJNnS.jpg


6-pin cable rated for 150w is actually not accurate, the story is initial pcie power cable is only 6-pin they rated it for 75w, but there's need to deliver more than 75w, so they changed the spec, pcie power should be rated 150w, to differentiate which cable can deliver 75w (older spec) or 150w they add 8-pin connector, which another 2 pin is not to deliver power, but only to signal GPU if these another 2 cables is connected it means the cable is on newer spec (150w), gpu can take up to 150w, but if only 6 pins are connected gpu only allowed to take 75w since the cable is assumed on older spec which is rated 75w

both 75w and 150w connector deliver power through 3x 12v pins, so it doesn't matter 6-pin or 8-pin connector since both are using 3 pin to deliver power, what matter is the diameter of cable (which is rated in awg), 18-16 awg wire can be configured for 6-pin, 6+2pin or 8 pin, but 24-20awg only allowed to be configured as 6-pin, since 24 awg wire each can't deliver more than 25w of power

most current PSU cable are using 18awg or 16awg, so it is safe to assume it can deliver up to 150w for 6-pin/8-pin connector

now about that 570 pulse mini, if the gpu use 6-pin connector, then the gpu will only take 75w from gpu power connector, so if i assume that "less than 150w" words are meant to be "it never exceed 150w, but it can take up to 150w" then when it take 150w, gpu will take 75w from 6-pin connector on gpu, and another 75w from the riser, since molex are rated 50w, its an overcurrent for molex connector

I have been using one PSU to power the risers and one PSU to power the GPU for all my mining machines. Never had a problem.
I use one of these to power the cards:
https://www.newegg.com/Product/Product.aspx?Item=9SIA7GT5NK5071

And then a 600-700w to power the motherboard, SSD, and risers. Would that normally cause a problem?

on most case it wont be a problem, as long as both PSU are connected to same ground wire, since both PSU ground ended up on the same home power plug it will be on the same earth ground, but on some case, there are different circuitry between two kind of PSU which make their ground is not equal or some other cause, then some problem

Thanks for clarification. What if I use a power cable joiner? Will that help with the single ground?

Currently both PSUs are plugged into the same surge protector.

Eventually they will be on the same PDU once I get that installed.

This is so much great information that I had no idea about. Thank you so much, very informative and important!

In other words, you're saying that 6-pin connectors on the risers are needed. However, if that's the case, then how come it seems that most miners (well, that I've read about, perhaps not "big-time miners" though, but they do just fine with molex on their risers. Most cards use more power than the Pulse Mini. Of course, under volting is an option that many do so that would explain it.

Let's say the card uses 150W and since it's being powered by 6-pin cables, it also draw 75W from the PCI slot. Obviously that's not a good idea for molex cables then. However, if I under volt each card to make sure it never goes above 125W (lower of course to have some head room), it should be fine until the new 6-pin risers arrive, correct?

For example, if I under volt it enough to get to 110W max, would it still draw 75W from the 6-pin cable and then another 35W from the molex cable?

Thank you again for all your answers, you're extremely helpful!

Edit: Are you sure I can't use two molex risers on a single cable? Most people I've read about claim that it works just fine but that three is too many.

i don't have that deep knowledge of internal circuitry of PSU, what i did and assume is just to get into safest first than into the unknown
so i will just make (riser+gpu) on same PSU because i know that riser power and gpu power are somewhat connected inside gpu,

unlike on [ gpu <-> riser <-> motherboard ] connection, gpu and motherboard are power disconnected because when i see the riser pin trace it bypass the power pin from motherboard, and use their own power from molex/6-pin instead of from motherboard pcie slot

and also i have an experience on earliest day of gpu mining, when there are no powered riser available, i use different PSU for GPU and motherboard, and of course GPU are slotted directly into the motherboard since at that time there are no so called "gpu riser for mining", and then the motherboard just explode, taking that experience i never split PSU between power connected devices

I have a few hundred rigs that all call bullshit on this. All of them are setup with the risers powered off of molex to sata power on the atx power supply and all of the video cards off of high end server PSUs. Out of thousands and thousands of connectors I have never seen one have problems.

these problem started when AMD launched RX series GPU with only 6 pin powered and use up to 75w on the peak from pcie slot

i've been mining since HD5xx series, into HD7xxx and R9... there are no case of riser power cable melted, because those early gpu mostly use power only from GPU's power connector, and only little bit from PCIE slot


each gpu have different circuitry, bios and driver
some GPU split between GPU Core power (from GPU pcie connector) and GPU Memory Power (from PCIE Slot), some use shared power, by undervolting surely it help but gpu has their own allocation of power which i am not sure, that's why i will just take the safest option by using pcie powered riser

no i am not saying you can't, but it safer to use pcie power, I personally had use 3 riser in single molex which is ended up in PSU connector melted (the riser connector end was just fine), then I use 2 riser for single molex which most of the time just running fine, but some rig melted at some time when the room is hot enough, but until now i never had issue of melted connector when using pcie powered riser

https://i.imgur.com/HpfUPyW.jpg
these cable are my enermax PSU's molex (PSU's endpoint) , ran 2 riser for each cable

https://i.imgur.com/hLlsDri.jpg
if I use 2x Molex to PCIe converter to powerup PCIE 6 pin riser

https://i.imgur.com/jJIGVTc.jpg
never use molex to sata converter

I understand that it's safer to go with the 6-pin risers. I'll order those. However, I have molex risers incoming already - which I always thought as temporary because I could get them fast. Question is if I can use them for a week.

I've read that three risers per cable will melt it when it comes to molex. That's why I was thinking two risers per cable and three cables.

You say that some cables melted when the room was hot enough - can you remember how hot the rooms was when they melted - or take a guess at least?


Now, I don't know much about electricity but pretty much everyone who has an AsRock BTC motherboard and use the two molex connectors on the motherboard claims that it works absolutely fine with all six GPU's and unpowered risers. I don't doubt you (I'll order the 6-pin risers to be safe!), but it seems to me that only two molex connectors on the motherboard nets you another max 100W, but that's apparently still enough for six GPU's on that motherboard. Or am I missing something?

My suggestion is use as many PSU peripheral cables as you have. If you have enough to do 1 per, do that. If you can do 2x2 +1 + 1, then do that.

Right, I'll only be able to do 2+2+1+1 in that case since I have two molex cables left over that I don't use from my PSU that I have on my gaming PC. I'm assuming they'll work since the two PSU's are the same model but different wattage. One is EVGA G2 750 and the other (for the mining rig) is EVGA G2 1300.

I'm a new comer to the forum, and I'm trying to get one last bit of info before I can assemble my 8 GPU rig. I was hoping you could answer my query regarding a similar setup.

I'm planning a 8 GPU build, in which I've ordered the following components:

• 2 x EVGA SuperNOVA 850 Titanium PSU
• 8 x GTX 1070 Founders Edition
• Risers (6 Pin 006c as recommended in the wiki https://www.reddit.com/r/EtherMining/wiki/hardware/risers)

Here's a pic of the connections available in my PSU: https://imgur.com/a/j5TII

What I'm confused about is which slots do I connect the risers? I feel I have the following options:
1) Use a PCI-E splitter, so that each VGA slot is used by 1 GPU and its riser (got the idea from your aforementioned post)
2) Put each GPU in its own VGA slot, and its corresponding riser in a 6 pin slot in the same PSU (will have to use up a VGA slot for the third GPU)

Option 2 limits me to 6 GPUs in this rig, though my mobo is capable of 8 (z370-A). I'd obviously like to have a 8 GPU setup, but I don't want to use an option that is remotely unsafe. Am I being too paranoid about the whole thing (u can tell I read the Risers section in the wiki quite a few times!) ?

A cable w/ an 8 pin termination should be able to supply 150W according to the PCIE spec - if your GPU is drawing less than 150W, you should be able to split such a cable between the GPU and riser.  The better option would be to simply use an 8+6 split (Y) cable - 8 pin to the GPU, and 6 pin (w/ an extender if necessary) to power the riser.  That way you can be certain the cable is rated for that load (an 8 + 6 termination should supply 150W + 75W per PCIE spec,) assuming your cards draw less than 225W (which they absolutely should for mining.)  Since you only get two of those types of cables w/ your chosen PSU, you could use the 2 x 4 pin peripheral (a.k.a. molex) cables to power your other 2 risers.

A couple other notes:

1. The draw on an 8 pin termination of a PCIE cable is spec'd to 150W, but the cable likely can provide closer to 180W (3 hot pins @ 5a x 12v or 60W each,) while the supply is actually probably closer to 240W (4 hots x 60W,) so you're probably fine just splitting a single 8 pin terminated cable if GPU TDP is < 180W.  But if you want safest, the config above works (and saves you from buying additional splitters.)

2. The FUD around sata power is a little overblown.  While a sata power connector easily provides the 75W max allowed for a PCIE x16 connector, the main concern is that the PCIE spec allows for 5.5a over the 12v rail (66W) on the MB connnector, while a sata power cable only provides 3 12v pins @ 1.5a each, or 12v @ 4.5a (54W) total.  However, most modern, optimally tuned GPUs run around 75-150W for mining, so a single 8 pin PCIE power cable likely provides all the 12v power the card needs, w/ the MB connector/riser providing the 5v, and minimal (if any) 12v.  Of course, this split is up to the GPU manufacturers, and they *could* technically pull all available (66W) 12v power from the MB bus before utilizing the PCIE power cable (or split as evenly as possible across the 2 sources,) but that is not how I've seen power delivery implemented on any recent card I've used.  My cards all run in the 100-150W range, and the ones using risers powered by sata cables are doing just fine.

3. Ver 006C is pretty old for the risers.  I would recommend at least ver 008s, like these: https://www.amazon.com/EXPLOMOS-Graphics-Extension-Ethereum-Capacitors/dp/B074Z754LT

Thanks a lot for the detailed reply - I learned quite a bit from it, and have ordered the 008 risers as per your recommendation!

Two follow-up queries:

• You mentioned I could use 2 x 4 peripheral cables (molex) to power the other two risers (ones which aren't connected using risers). Did you mean that I use each of the 8 pin CPU ports in my PSU (marked as CPU1 and CPU2) for 2 molex cables (referring to the back of my PSU whose pic I've linked before)? If not, I don't see any more ports that are capable of handling the 4 pin Molex's? 
• I'm trying to get identical power inputs for each of my GPUs - so, I'm considering buying 2 more Y splitters ( 8 + 6 split(Y) to 8 pin) so that each of my 4 GPUS and its corresponding risers are powered using the Y cables. Is there anything wrong with that idea, other than the fact I'll have to order extra splitters? Speaking of which, I should be able to purchase EVGA splitters from the manufacturer's website, right, or would any amazon Y splitter would do?

Thanks!

Hi all, i'm building a 6x1080ti rig for the first time and got some panic with all the sata risers stuff to be honest. I've been reading this post and like 1389349539 more but still can't think clearly what should I do, and that's why I ask for some help here, would appreciate it a lot.

As i said, its 6x 1080 ti and I assume will be underpowering them to more or less between 150 and 180W. Got the corsair ax1600i (http://www.corsair.com/en-eu/ax1600i-digital-atx-power-supply-1600-watt-fully-modular-psu-ww) and also my risers have only 6pin power connections.

- Can i use each PSU PCIe connectors to 1GPU + 1 riser, using a split cable (i believe 8pin to 2x 6pin splitter)? Is that safe/capable of providing the gpu+riser the W they need?
- Should i use 1 PCIe to 1 GPU and the other 2 PCIe for 3 risers each?
- Any other better combination/s?
- Not any of what i said...  ??? ???

Thank you very much in advance

My graphics cards take two PCIE connectors each and draw a lot of current.  I'm not sure it would be advisable to use a splitter and have that one cable provide all the power for both the GPU and the riser.

If I can use molex I will use that over sata.

which 1080ti do you have?

I thought they all have 2x8pin power connectors?

They are asus strix, they're coming in this morning I hope. If that's the input then I can only connect 4 1080 to that psu, having 8 pcie outputs?

There is so much great info on this thread. I have tried searching for some answers but I have come up empty handed.

My setup;

6 x MSI RX 580 8gb.
Biostar 250 BTC PRO
Version 6/7 Riser (Only Molex Connection).
Gigabyte 1200XP – don’t give enough cables and don’t sell individual cables.

I am about to introduce another 6 GPU’s to this setup with another PSU.

PROBLEM: Setting up the first 6 GPU’s with risers, I used all the molex cables and was left with only some 6 PIN to 4xSATA cables. So, when it came to powering the two 4 PIN AUXPWR ports on the Mobo, all I could use was a single 6 PIN to 4xSATA cable then use SATA to molex adapters to plug into each of the two AUXPWR ports.

On a scale of severity, how bad is that?

Those adapters always feel cool though.

If I can find a website/service to make some more molex cables for me that work with this particular PSU, is it still possible to use one single cable to power both AUXPWR ports?

Last question, there is allot of warnings about Molex to SATA adapters and to not use them with risers. Does that go for SATA to Molex as well, or all adapters that are sold ? i have a splitter; 8 PIN female that splits to 2x6+2. Are these a risk as well?

Using Sata cables with the sata-molex adapters to power the motherboard is perfectly safe, the motherboard doesent use any power from them if you are using powered GPU risers, which in your case you are. You dont need to have those AUXPWR ports plugged in at all.
Sata to molex adapters should be avoided for powering risers (can be used with nvidia cards, not with amd). If you only have sata cables, and need to power risers, then buy the sata power type risers.
As for the 8pin-2x6 splitters, those are pretty safe always.

Just a quick one on this maths. I was wondering whether to use a sata cable for a single riser, or split a pcie cable between two risers on a rig. Kinda concluded that it would be worse to split the pcie cable, as pcie max 75w, divided by 2 risers is 37.5w - less than sata @54w max...?

(Sata max 54w: http://www.playtool.com/pages/psuconnectors/connectors.html)

Thanks for this useful information.

I have been using Sata cables to power my risers and did burn one sata / molex cable converter a while back.

I will re-configure my rigs now after reading this.

Thanks again.

Thank you so much for this. I will lose both those SATA to Molex adapters and either buy some of those 8s risers which have SATA, Molex and 6 Pin connectors. Then decide to either go with the SATA connection or use the Splitter and the 6 PIN connection.

Many thanks again.

Hi Deadsix,

I'm wondering if i could call on your knowledge once again.

Do you think it's possible to power a headless rig; 1x RX580 GPU, 1x Mobo/CPU/Ram/SSD, 1x Ver. 8s Riser by a Gold Standard 650W PSU. There are two local options for the 650W PSU in Superflower and Antec. Antec is about $30 cheaper than the Superflower.

Im thinking 250W for combined (SSD,Mobo,CPU,RAM) and 150-170W for GPU/Riser ? = 400-420W. Which is approx 64% of the 650W load of the PSU.

This should be more than ok, right ?

The other GPU's and risers are powered by a Server PSU.

I run several 4 x RX 570 rigs on 750W Gold PSU's, so 650w is more than enough for your need. Superflower makes some very good PSUs, and Antec is decent in the gold and above category so either of them will be suitable.

You are the best ! thank you.

Sorry for the late reply - hopefully you've already gotten your answers by now, but just in case...

1. sorry, for some reason I thought I saw 2 perif ports on that PSU - looks like it only has one.  You should have a cable w/ multiple 4 pin peripheral (molex) adapters for that port.  So you'd have to either chain 2 cards on a single perif cable, use one perif and one sata cable (assuming your card pulls less than 4.5A from the risers 12V,) or buy additional PCIE cables.  You can't just use the CPU ports - those are wired differently.  There are converter cables on ebay/amz, though you have to make sure you're getting the ones that are CPU->PCIE, and not just PCIE extenders (double check the wiring yourself - I've read reviews that make it sound like the wrong item gets shipped sometimes.)

2. Nothing wrong w/ using all 8+6 cables - def the safest option, assuming you're under ~225W per card.  You can't purchase individual cables from EVGA - they only sell bundles, which are ridiculously expensive and you get a bunch of crap you don't need.  You can get aftermarket ones from places like moddiy or cablemods (https://store.cablemod.com/configurator/)  Generally, you can't get these from amzn, as the supply side termination is unique to the PSU manufacturer.