USB Risers problems

[raidersan]

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!

[Redrose]

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

[raidersan]

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?

[Amph]

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

[raidersan]

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

[Amph]

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

[raidersan]

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. 

[Amph]

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

[RastoMan]

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.

[AlphaSun]

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

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

[Amph]

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

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

[Kewatia]

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

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.

[raidersan]

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

Can you provide a link to a reliable source?

[reb0rn21]

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

[AlphaSun]

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.

[raidersan]

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

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

[Amph]

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

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

[raidersan]

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?

[reb0rn21]

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!

[raidersan]

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