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I have a 4 rigs with 6 GPUs on each, all using powered 1x-16x Risers. The GPU's are mixed bag of 7950, 7970, 280, 290, 390, and exactly 2 7990's per rig.
Initially all goes well but I am constantly getting failures of the risers, and I cannot put my finger onto the cause. Is it bad quality of the riser, are some cards trying to extract too much power out of them? I have risers coming various sources on eBay but I suspect that most of them come from China anyway. None of them are carry a brand though.
Could it be linked to the PSU?
If it is as I suspect the quality of risers, where do you get quality ones, preferably in Europe?

Many thanks!

I get mine on Amazon. Did you wired molex cables to the motherboard ? Do your risers have a kind of aluminium paper on them ?

I have molex cables from each riser to the PSU - I have never bought a riser with aluminium, where is that aluminium placed? Mine always have a spongy bit at the bottom to have shorts but they do end up falling after a few weeks with the heat. Do you have a link to the risers you bought?

usb risers are unnecessary, i'm running 5 x 970 without issue, using the standard ribborn risers, just buy h81 pro btc

How many GPU's will the ProBTC take without risers? I have 6 cards, 8 core on each MB

only 1, you need x1 x16 risers, there is really no need to spend much for usb riser, i've always used standard riser, and they always worked good, just don't buy from unreliable source

Sorry I expressed myself poorly. How many GPUs will a pro BTC be able to feed off the motherboard itself without powered risers, just with ribbon cable risers? In my rigs I have 6 cards, totalling 8 Tahiti GPUs. That seem a lot of power for just the 2 molex on the ProBTC board. 

each molex can provide 132 watt, so you have 264w, plus the motherboard can provide 25w for each x1 slot and 75w for the single x16 slot, so a total of 200w

464w in total can be provided by the motherboard, it's more than enough for any 6 x card setup, minus those 2xchip gpu, like 7990

The 7990 uses little power from the motherboard PCIE slots.

One power cable from the PSU will have 3 to 4 molex connectors, does it mean each cable can provide up to 500W?

if they are all 4 pin yes, but i remember that this is not the case, and anyway one cable would melt in that way, but i'm not sure about this

I  have a few modular PSUs, all of them have 3 to 5  4pin molex connectors. So I will be very careful.

Can you provide a link to a reliable source?

there are some bad risers at ebay and some good, shame you can not know till you receive it

also 7xx 2xx cards most draw little current from PCI-e slot (5-20w) but 3xx series some draw a lot more so bad riser will melt, even good riser I would not hold more of 60W a bad one might fall even on 30-40w or less

I think most or all the risers will not melt at 60W. 60W is just 5A, it most wires can withstand that. It is the PCIE slot, that is the problem.

Is there nobody here who can point me to their source online for reliable risers?

bought a bunch from this guy, all working perfectly http://www.ebay.co.uk/itm/NEU-25cm-Extender-Riser-Flex-Kabel-PCI-E-PCIe-x16-Karte-x1-Slot-Cable-/291076040426?hash=item43c57be6ea:g:tu8AAOxyiRlSbV2F

he rised the price, it was much less before

Thanks but I would like to stick with powered USB ones. Anybody with a source of reliable ones?

None USB risers can hold more then 40W!!! (that I know) the problem is USB cable, sata power adapter, etc too match resistance!

Just buy quality 1x to 16x riser with molex connector!

Ok thanks for that, can you provide a link for a reliable vendor of those?

USB 3.0 cable should be able to provide 100W. But sata power is only 3x1,5 (3pins)=4,5A/12V= 54W.
So USB risers for RX480 should be powered via Molex, not via Molex-Sata adapter.

You can also use the old ribbon cables with the +12V molex connected to the +12 of the PCIE extension lead.

I purchased a few of these risers with the 6 pin PCIe power connectors so I could use them with my server power supplies.  They've been working pretty well for me so far.

https://bitcointalk.org/index.php?topic=1418963.0 (https://bitcointalk.org/index.php?topic=1418963.0)

I am also interested for  a durable riser, many thanks.


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You will need a USB riser with connection of the +12V both to the PCIE +12 V slots and the PSU +12V.

Had a experience with a bad riser thats a bit more "unusual"

Got another gpu to finish off this small rig from newegg and at first all went well.  But after a bit of mining the new gpu would fail the opencl call and crash and id reboot start mining again and the same thing after about 30mins-1hr.  I figured it was a faulty gpu so I sent it back and got a replacement but of course I thought about it and should have tested the damned riser.  I should also mention that if I would plug the gpu via the riser that to the main x16 slot on the mobo that it would fail to boot and hang.

So today I got my new gpu and I got it all set up and mining away, seemed the problem was fixed and I chopped it up to a bad gpu as I thought at first.  After 8 hours of mining the new gpu crashed and the miner restarted crashed again with 40 mins.  So then I swapped out my riser with a good one, in the gpu next to it and it booted normal and seems to be working as it should.

So the point of this story is that these damn risers and electronics in general can have problems where they do not fail completely.  I have wasted a good amount of time trouble shooting it, sending the gpu back and now I need a new riser to mine on the gpu.  So if you have a problem like this that doesn't seem to add up, suspect the riser!

I've never seen a riser like those before...those look really interesting.  Anyone know of an online vendor selling these?

you can do it yourself
its not so hard? or buy in aliexpress

Technically, wouldn't padrino technically be an online vendor?  I've bought stuff from him before and he's great to work with.

I haven't looked to carefully into the spec, but I know that with the risers using the Molex connector, they're definitely using both the 5v and the 12v power supplied - whereas this riser would only be providing 12v from the PCI-e connector, so presumably drawing 5v across the ribbon cable.  

On my 6 card systems, each card generally draws about 1a at 5v across the riser molex connector... That's what steered me away from these solution combined with the fact it doesn't have mounting points, although I loved the fact they use PCI-e cables as that's a big hassle for my configurations.

I took a look at my riser that had issues to see if there was anything I could fix on it.

I found one of the pins on the back had a thin solder bridge shorting it out or getting one the data connections messed up during an opencl call, so I scratched it with my knife and seems to working properly now.  Simple fix but it caused me a lot of headache

Absolutely not. You will burn them, without a good OCP protection on the +12V from the PSU. If you've got a good OCP instead, on the female molex and sata connectors, the PSU will simply shut down. Be careful on the power delivery, it's thr MAIN source of issues

gpushack has good risers and they ship fast.

How did I never see that before?  AWESOME - thanks!

P.S. Here's a link:  http://gpushack.com/search?type=product&q=riser