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
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.