Question on PCI-E raiser cable and GPU miner

kingcolex

sr. member

Activity: 254

Merit: 1258

Quote from: tbonetony on June 13, 2015, 12:35:22 AM

Hi folks,

I am about to start building a gpu miner myself. Before I place orders, I have some questions on the raiser cables. Nowadays they all seem to come with either SATA or Molex power ports. But what exactly needs such power? Does this mean that once my GPU is connected with the raiser cable (on the x16 terminal), it would no longer require PCI-E 6/8 pins to power up?

I could not find relevant answers maybe this question is just too naive.

Thanks for your help.

I have a couple gpu rigs and here is how it works, the motherboard feeds up to 75w to the cards, if they have PCI-E pins they still need to be powered (this is how some graphic cards can use up to 500w), the more powerful the card the more power it will need but usually 2 6pins will cover it. The riser needs a separate power because you're usually converting from pci x1 to x16, x1 allows less power from the motherboard. Power to the risers help keep things safe, without them too much power will be trying to go through your motherboard and likely melt or burn something.

TL;DR Make sure you have the risers powered or expect something to melt.

bathrobehero

legendary

Activity: 2002

Merit: 1051

ICO? Not even once.

Quote from: BitmoreCoin on June 18, 2015, 05:40:20 AM

H61/81 is good as they have two on board molex socket. These cards are built for mining, so they are robust.

With powered USB risers I don't use the molex sockets on the motherboard. While PCI-E 1x sockets can only output 10W, not even that is being pulled from there.
The cards pull everything from the riser, therefore the PSU itself so I think it's pointless to use those sockets and those sockets are only there for the early unpowered risers but nobody uses them anymore.

BitmoreCoin

sr. member

Activity: 406

Merit: 250

Quote from: Corsa1r on June 17, 2015, 06:28:37 AM

Quote from: BitmoreCoin on June 16, 2015, 02:52:58 PM

Quote from: djm34 on June 14, 2015, 06:59:40 AM

Quote from: BitmoreCoin on June 14, 2015, 06:34:10 AM

If you buy the ASrock pro BTC H61 or H81 http://www.asrock.com/mb/Intel/H81%20Pro%20BTC/
you do not need PCIE riser.

If you do not overclock, and undervolt you GPU, you only need to have 20-50% of the cards with powered riser.

... and use only one gpu, yep you don't need a riser... otherwise I want to know how you fit the gpu into the small pcie...

... and plugging the molex into mobo increase the chance that the mobo will burn as well

Sorry, I mean you do not need powered risers. I have 8 GPUs on the 6 slots, working fine.

8 gpus? How do you achieve this with only 6 slots?

I use dual gpu cards such as 7990. 4X7990 = 8 GPU. 3X7990+2X7970 = 8 GPU.

I use as many gpu as possible to reduce the overhead cost of system. So the total cost (electricity) per card is lower.

If you undervolt and underclock, you will not use the full 75W PCIE power/current.

H61/81 is good as they have two on board molex socket. These cards are built for mining, so they are robust.

djm34

legendary

Activity: 1400

Merit: 1050

Quote from: Corsa1r on June 17, 2015, 06:28:37 AM

Quote from: BitmoreCoin on June 16, 2015, 02:52:58 PM

Quote from: djm34 on June 14, 2015, 06:59:40 AM

Quote from: BitmoreCoin on June 14, 2015, 06:34:10 AM

If you buy the ASrock pro BTC H61 or H81 http://www.asrock.com/mb/Intel/H81%20Pro%20BTC/
you do not need PCIE riser.

If you do not overclock, and undervolt you GPU, you only need to have 20-50% of the cards with powered riser.

... and use only one gpu, yep you don't need a riser... otherwise I want to know how you fit the gpu into the small pcie...

... and plugging the molex into mobo increase the chance that the mobo will burn as well

Sorry, I mean you do not need powered risers. I have 8 GPUs on the 6 slots, working fine.

8 gpus? How do you achieve this with only 6 slots?

what I meant is that you require the mobo to draw 75W per card so 6 or 8 gpu with one additional molex plugged into the mobo is still somewhat risky
your system is drawing 450W through the mobo (not taking into account cpu, memory etc...) so yes it might burn...

(at that level powered riser are, in my opinion, a better solution)

Corsa1r

member

Activity: 89

Merit: 10

Quote from: BitmoreCoin on June 16, 2015, 02:52:58 PM

Quote from: djm34 on June 14, 2015, 06:59:40 AM

Quote from: BitmoreCoin on June 14, 2015, 06:34:10 AM

If you buy the ASrock pro BTC H61 or H81 http://www.asrock.com/mb/Intel/H81%20Pro%20BTC/
you do not need PCIE riser.

If you do not overclock, and undervolt you GPU, you only need to have 20-50% of the cards with powered riser.

... and use only one gpu, yep you don't need a riser... otherwise I want to know how you fit the gpu into the small pcie...

... and plugging the molex into mobo increase the chance that the mobo will burn as well

Sorry, I mean you do not need powered risers. I have 8 GPUs on the 6 slots, working fine.

8 gpus? How do you achieve this with only 6 slots?

BitmoreCoin

sr. member

Activity: 406

Merit: 250

Quote from: djm34 on June 14, 2015, 06:59:40 AM

Quote from: BitmoreCoin on June 14, 2015, 06:34:10 AM

If you buy the ASrock pro BTC H61 or H81 http://www.asrock.com/mb/Intel/H81%20Pro%20BTC/
you do not need PCIE riser.

If you do not overclock, and undervolt you GPU, you only need to have 20-50% of the cards with powered riser.

... and use only one gpu, yep you don't need a riser... otherwise I want to know how you fit the gpu into the small pcie...

... and plugging the molex into mobo increase the chance that the mobo will burn as well

Sorry, I mean you do not need powered risers. I have 8 GPUs on the 6 slots, working fine.

djm34

legendary

Activity: 1400

Merit: 1050

Quote from: BitmoreCoin on June 14, 2015, 06:34:10 AM

If you buy the ASrock pro BTC H61 or H81 http://www.asrock.com/mb/Intel/H81%20Pro%20BTC/
you do not need PCIE riser.

If you do not overclock, and undervolt you GPU, you only need to have 20-50% of the cards with powered riser.

... and use only one gpu, yep you don't need a riser... otherwise I want to know how you fit the gpu into the small pcie...

... and plugging the molex into mobo increase the chance that the mobo will burn as well

BitmoreCoin

sr. member

Activity: 406

Merit: 250

If you buy the ASrock pro BTC H61 or H81 http://www.asrock.com/mb/Intel/H81%20Pro%20BTC/
you do not need PCIE riser.

If you do not overclock, and undervolt you GPU, you only need to have 20-50% of the cards with powered riser.

tbonetony

sr. member

Activity: 441

Merit: 250

No zuo no die why you try, u zuo u die dont be shy

Thank you all for your advices. Really helped!

bathrobehero

legendary

Activity: 2002

Merit: 1051

ICO? Not even once.

Quote from: djm34 on June 13, 2015, 12:44:00 PM

well... I had the problem on my secondary psu which powers my 780ti (actually it burnt at the other side + on the psu cable it was a cheap one).

forgot to mention: monorail psu or it will burn Grin

but lets face it all these problems are probably more related to the cable than anything else

Yes, I bulk-bought a few dozen risers with cables and tested quite a few of them and some cables don't contact with the riser as well as others so some cables get warm, others get hot while most remain cold. I can't see anything that would imply poor contact but it's always the white plastic part that gets warm. However, I always only had warm cables with non 6/8 pin powered cards mining something power hungry like scrypt (oh cointellect).

Oh yeah power supplies... when I started of course I ordered multi rail PSUs (EVGA SuperNOVA NEX650G) and they turned the hell off as soon as I started mining with 4 cards or more. Then I sent them back and got two single rail PSUs (XFX PRO 650W) which are louder than all my cards combined so I decided not to go lower both in size and quality than EVGA SuprNOVA G2 850W and 1300W PSUs which are amazing and have 10 year warranty on them iirc.

djm34

legendary

Activity: 1400

Merit: 1050

Quote from: bathrobehero on June 13, 2015, 12:22:17 PM

Quote from: Grout on June 13, 2015, 10:56:30 AM

Quote from: djm34 on June 13, 2015, 09:12:22 AM

also avoid using the sata-molex cable as it can burn...
don't put more than one card per cable (or molex grape whatever it is called) or it can burn
don't use a cheap psu, or it can burn.

probably better actually to buy several small good psu than a big one or it will burn...

in summary: there are non negligible chances it will burn Grin

Whatever hardware you choose to use in your rig, its hostname should be firehazard.yourdomain.com Grin

Yep!

To be fair a 750 Ti which doesn't have any 6/8-pin burned this, cards which can pull additional electricity from 6/8-pins are not as likely to burn it if you only put 1 card per cable as said above.

well... I had the problem on my secondary psu which powers my 780ti (actually it burnt at the other side + on the psu cable it was a cheap one).

forgot to mention: monorail psu or it will burn Grin

but lets face it all these problems are probably more related to the cable than anything else

bathrobehero

legendary

Activity: 2002

Merit: 1051

ICO? Not even once.

Quote from: Grout on June 13, 2015, 10:56:30 AM

Quote from: djm34 on June 13, 2015, 09:12:22 AM

also avoid using the sata-molex cable as it can burn...
don't put more than one card per cable (or molex grape whatever it is called) or it can burn
don't use a cheap psu, or it can burn.

probably better actually to buy several small good psu than a big one or it will burn...

in summary: there are non negligible chances it will burn Grin

Whatever hardware you choose to use in your rig, its hostname should be firehazard.yourdomain.com Grin

Yep!

To be fair a 750 Ti which doesn't have any 6/8-pin burned this, cards which can pull additional electricity from 6/8-pins are not as likely to burn it if you only put 1 card per cable as said above.

Grout

full member

Activity: 139

Merit: 100

Quote from: djm34 on June 13, 2015, 09:12:22 AM

also avoid using the sata-molex cable as it can burn...
don't put more than one card per cable (or molex grape whatever it is called) or it can burn
don't use a cheap psu, or it can burn.

probably better actually to buy several small good psu than a big one or it will burn...

in summary: there are non negligible chances it will burn Grin

Whatever hardware you choose to use in your rig, its hostname should be firehazard.yourdomain.com Grin

djm34

legendary

Activity: 1400

Merit: 1050

also avoid using the sata-molex cable as it can burn...
don't put more than one card per cable (or molex grape whatever it is called) or it can burn
don't use a cheap psu, or it can burn.

probably better actually to buy several small good psu than a big one or it will burn...

in summary: there are non negligible chances it will burn Grin

Grout

full member

Activity: 139

Merit: 100

Quote from: tbonetony on June 13, 2015, 12:35:22 AM

Hi folks,

I am about to start building a gpu miner myself. Before I place orders, I have some questions on the raiser cables. Nowadays they all seem to come with either SATA or Molex power ports. But what exactly needs such power? Does this mean that once my GPU is connected with the raiser cable (on the x16 terminal), it would no longer require PCI-E 6/8 pins to power up?

I could not find relevant answers maybe this question is just too naive.

Thanks for your help.

Yes, you need to connect the 6/8 pins. Powered risers are there to protect the motherboard when you have several GPUs in you system.
Each card can pull up to 75W from the PCIe port. That's OK for 2-3 cards. But if you have 6, that's 450W total and I wouldn't risk pulling that much from the motherboard.

kotarius

sr. member

Activity: 340

Merit: 250

Quote from: tbonetony on June 13, 2015, 12:35:22 AM

Hi folks,

I am about to start building a gpu miner myself. Before I place orders, I have some questions on the raiser cables. Nowadays they all seem to come with either SATA or Molex power ports. But what exactly needs such power? Does this mean that once my GPU is connected with the raiser cable (on the x16 terminal), it would no longer require PCI-E 6/8 pins to power up?

I could not find relevant answers maybe this question is just too naive.

Thanks for your help.

You must always connect 6-pin and 8-pin PCI-E power to GPU. There are never any exceptions to this.

bathrobehero

legendary

Activity: 2002

Merit: 1051

ICO? Not even once.

The x16 PCI-E port can supply 75 watts, the 6-pin cable can supply an additional 75W and a 8-pin can 150W.

But the x1 PCI-E slots can only supply 10W so you have to feed the riser with 75W via molex or SATA instead (Assuming you use PCI-E x1 powered USB risers like these: http://cryptomining-blog.com/wp-content/uploads/2014/03/pci-express-x1-x16-usb-30-extender.jpg) so that only covers the 75W and you still need to use 6/8-pin connectors.

tbonetony

sr. member

Activity: 441

Merit: 250

No zuo no die why you try, u zuo u die dont be shy

Hi folks,

I am about to start building a gpu miner myself. Before I place orders, I have some questions on the raiser cables. Nowadays they all seem to come with either SATA or Molex power ports. But what exactly needs such power? Does this mean that once my GPU is connected with the raiser cable (on the x16 terminal), it would no longer require PCI-E 6/8 pins to power up?

I could not find relevant answers maybe this question is just too naive.

Thanks for your help.

Topic: Question on PCI-E raiser cable and GPU miner (Read 1690 times)