Topic: sapphire rx470 nitro with 1x to 16x riser cable (Read 564 times)

Yes, indeed I meant Amps. Thank you for pointing that out. Corrected.

clearly not 4.5 watts, more like 54W (you probably meant amps at 12v)

Motherboard manufacturers recommend no more than three GPU's per motherboard unless they have additional 4-pin Molex connectors like the H81 BTC or variants. Even in this case, I still use powered risers. Get the USB type variants like this one:
http://www.ebay.com/itm/Slim-PCI-E-Express-1X-to-16X-Riser-Adapter-USB-50cm-Cable-w-MOLEX-Power-Adapter/222148816398?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D2%26asc%3D39823%26meid%3D676f67ca3aba4bd2b4541b1552a49c19%26pid%3D100005%26rk%3D1%26rkt%3D6%26sd%3D191856126605

I like this one as it has a nice adapter that terminates into a 4-pin Molex. Do not hook more than two of these up to a single Molex run to your PSU. If you do get the ones that come with a SATA to Molex adapter cables, toss those adapters out and plug your 4-pin Molex connectors directly into the riser board itself.

As far as your technical answer, the PCIe slot can supply up to 75 watts to the GPU and remain within specification. At three GPUs you are pushing up to 225 watts through the mobo, not counting its usual load with CPU, Fans, memory, etc. Now this is peak value and depending upon many factors, including the card make/model, algorithm you are mining, temperature of the card and its environment, overclocking, and so on, this value may be close to peak or a fraction thereof. So since it will be impossible to properly figure all of this out without lab type bench equipment, you would be advised to follow best practices.

So in the end it is up to you. You can follow the advice of the people who have had bad experiences and have learned from their mistakes or choose to wait until someone gives you that precise value you are hoping for and risk the consequences in the meantime.

Yes, mining is inherently dangerous, although it is an often overlooked aspect of the hobby/business. I am surprised more of us haven't burnt our house's down...

So while I am aware of the danger, I try to minimize the risks. Use quality components, do some research and figure out the maximum loads for wires, etc. For example, a SATA adapter can only supply 4.5 Amps (54 watts) to a powered riser whereas a 4-pin Molex connector can supply 9 Amps (108 watts) more than satisfying the 75 watt specification. Details like this do matter and knowledge is fire prevention.

Also, try not to keep you miners in areas with flammable materials, curtains, rugs, sheets on bed, etc. I have my miners in either the basement or in the garage on cement floors with only hard (Sheetrock) or cement walls nearby. I try to keep anything that may easily catch fire at least 6 feet away as sparks will fly a long ways. Also keep smoke detectors in the vicinity and of course outside your bedroom(s).

thanks for your answers
still don't know what to do
as some people highly recommend me to use powered risers,there are some who claim that the powered ones can be dangerous too.
my question is rather technical because I would like to know how much an 8-pin rx470 consums power from pciex 1 slot (as it has two more pins than the reference one, can those two extra pins provide enough power in order not to use a powered riser?)
I don't care about the price and type of the riser cables ,but different ideas about the powered  and non powered risers are a little annoying .
my rig again:
5 x sapphire rx470 8gb nitro (3 with simple 1x to 16x riser cables and 2 with simple 16x to 16x riser cables)
(so far everything is ok, no issues at all)
psu Coolermaster v1000
motherboard GIGABYTE F2A88X-UP4

many thanks

once I had one of the newly installed powered riser (1 out of about 30 that I had installed) exploding with flames searing the card for a couple of sec. So, it is not always fun and games with powered risers.
amazingly, card was fine, hashing nicely on another riser.

Yes, without powered risers any more than 3 GPUs will exceed your motherboard's capacity to feed them. While a good chunk of wattage does indeed go through the 8-pin connector, enough remains going through the PCIe bus to cause issues with more than 3 cards. Personally I never run more than 2 cards directly off the mobo, and most of the time it is either just one or they are all on powered USB risers.

The USB powered risers can be found easily for under $10 each, often less in multiples, so trying to save $10 or so when $100's or even $1,000+ of equipment is at risk does not make a lot of sense.

I'll add that I learned this the hard way way back in early Bitcoin/Scrypt  mining days as one non-powered ribbon cable got some warm it started smoking and melting until I heard a loud pop and the rig shut off. (I didn't notice the smoking and melting until after the rig popped). Another thing to look out for is if you use the Molex to 8-pin adapters, as these too are a weak link and can overheat. I had a couple of these melt down on me too. In both cases, they ran for day/weeks until the trouble first appeared. I am just glad it didn't happen in the middle of the night and the internal circuitry was able to shut them down.

Normally computers are pretty safe and are designed that way when running under there designed intention. Building hobbled together rigs and then pushing them to and in some cases beyond their limit is a sure recipe for disaster.

TLDR: get the powered risers.

8pin is what, 150W max? Check how much power your system draws, subtract CPU, divide by number of GPUs.
Just don't use the GPU-Z numbers.

hi there
i am using 5x sapphire rx470 nitro plus 8gb mining ethereum. Three of the gpus have been connected to pci x1 using 1x to 16x riser cables (they are not powered) .My question is that, given the fact that all my cards are connected to the psu with an 8-pin gpu cable (not a 6-pin) do i still have to change my riser cables with a powered one (reference rx470 cards have 6-pin connector and naturally the pcie slot is under pressure)
how much is it dangerous if i keep using the cables?
i have been minig for about a month.
thanks