Motherboard designed for mining, and better riser cables in this thread.

[pontiacg5]

Why did you buy x16-x16 risers? You should have got x1-x16.

There is no added benefit to mining using x16-x16 riser cards, only negatives.

First, the risers add latency. So, if you were planning on gaming on x16 risers you may need to rethink that plan.

Second, those risers are huge! You are blocking a lot of airflow for absolutely no reason. They are a pain to maneuver and route. They are also more expensive, because they are wider.

Lastly, you've got an extra 17 lanes of connections for no reason. If any one of those hundreds of solder points fails, it's likely the whole thing goes belly up and quits working for absolutely no reason. I also strongly believe the extra noise from all those extra lanes causes problems for people as well. PCI-e was not meant to travel along an unshielded parallel cable. Don't know how many of you have tried, but go untwist your cat5 network cable and see how well it works...

I see people adding 1x presence detect pin jumpers to x16-x16 risers all the time and I just have to chuckle a little...

[radi324]

Well, shows how much I don't know I guess... so should I just get powered x1-x16 risers instead? In that case I'll order some straight away

[pontiacg5]

I would get USB riser cables myself because they use individually shielded twisted pairs for data, but if you are dead set on cheap ribbon cables then I would get the x1-x16 powered version. Keep them short though, 7" or 19cm is standard IIRC. Longer ones may work, but like I said pci-e communication is a balanced pair of data lines. The longer (or wider, as in more pci-e lanes) they get, the higher the chance the noise can't be "comp'ed" out. If you get to that point, you'll have erratic mining behavior, or no mining at all.

http://en.wikipedia.org/wiki/Twisted_pair

[jackkiej]

I would get USB riser cables myself because they use individually shielded twisted pairs for data, but if you are dead set on cheap ribbon cables then I would get the x1-x16 powered version. Keep them short though, 7" or 19cm is standard IIRC. Longer ones may work, but like I said pci-e communication is a balanced pair of data lines. The longer (or wider, as in more pci-e lanes) they get, the higher the chance the noise can't be "comp'ed" out. If you get to that point, you'll have erratic mining behavior, or no mining at all.

http://en.wikipedia.org/wiki/Twisted_pair

Does it matter how long the usb cable is for the usb risers?

[radi324]

I would get USB riser cables myself because they use individually shielded twisted pairs for data, but if you are dead set on cheap ribbon cables then I would get the x1-x16 powered version. Keep them short though, 7" or 19cm is standard IIRC. Longer ones may work, but like I said pci-e communication is a balanced pair of data lines. The longer (or wider, as in more pci-e lanes) they get, the higher the chance the noise can't be "comp'ed" out. If you get to that point, you'll have erratic mining behavior, or no mining at all.

http://en.wikipedia.org/wiki/Twisted_pair

Thanks for the help, found it very valuable. So if I get these, do I need anything else with them? They're powered via SATA right?

http://www.aliexpress.com/item/PCI-E-PCI-E-Express-1x-to-1X-4x-8x-16x-Riser-Extender-Adapter-Card-with/944387438.html

[LostDutchman]

I read about fried Asrock Pro BTC boards when people used them with powered risers but also heard claims that without powered risers only 2-3 cards would work.

I'm planning on building a rig with an Asrock Pro BTC mobo in mind with 5 cards, but with 2-3 types of video cards, with different power consumptions. So what would be the safest route to take?

Always use powered risers and if you don't understand what I just wrote, let me put it a different way..............................

ALWAYS FREAKING USE POWERED RISERS!

There!

Get it?

Got it?

Good!

My $.02.

Not for the asrock H81 Pro BTC motherboard.  It provides supplemental molex power to the PCIe ports already, so powered risers would be redundant and likely to cause a short circuit as described in threads in the past.

What?

No, just no. Powered risers will never cause a short with the pci-e lane, no mater if the bus has supplemental power or not. 12V is 12V. 

I'd go a step further and say never use ribbon riser cables, but if I were to use those pieces they would certainly be powered. LostDuchman knows what he is talking about, use the powered ones no matter what mobo you use.

Thanks for your reply!

It gets difficult to educate the "Plug And Play" crowd!

My $.02.

[pontiacg5]

Does it matter how long the usb cable is for the usb risers?

Yes, there is a theoretical limitation. I believe USB spec used to be 10 meters, but USB 3.0 is likely different. I have used plenty that are 1M long and they work just fine. The extra shielding and twisted pairs are what lets a USB riser work while being so long though.  

Thanks for the help, found it very valuable. So if I get these, do I need anything else with them? They're powered via SATA right?

http://www.aliexpress.com/item/PCI-E-PCI-E-Express-1x-to-1X-4x-8x-16x-Riser-Extender-Adapter-Card-with/944387438.html

Yes, that is a good one. They are around for cheaper than that though. I've seen them down to $18 or so recently, check the forums, ebay, and litecointalk.org marketplace. You should not need to do anything to make these work like a champ. They even have built in 1x presence detect jumpers so you don't even need to do that!

Thanks for your reply!

It gets difficult to educate the "Plug And Play" crowd!

My $.02.

Not a problem!

[pilotchup]

Pontiacg5, could you please check your messages?

[pontiacg5]

Pontiacg5, could you please check your messages?

There are so many, asking so much...

I believe I found yours and replied.

[llamabucket]

I also have an order coming in with a bunch of these ASRock H81 Pro BTC boards, and am slightly electrically dumb
I've been scouring the forums looking for reasons why some people advise NOT to use powered risers and some people say to use them at all times.

I personally run regular motherboards and *always* power my risers. But there seems to be a lot of confusion with these boards and the two on board molex connectors.
Can someone please explain why it's impossible for a card to burn out if use both the on board and the risers molex connectors?

I keep seeing things like this on the web, and this guy seems to have a farm: https://bitcointalk.org/index.php?topic=414751.msg4560094#msg4560094

EDIT: just found another thread with problems (same dude chimes in here from the link above, but the OP is the one with issues): http://www.overclock.net/t/1456912/2x-asrock-h81-pro-btc-fried-cant-be-swapped-mobo-wont-boot-help-mining-rig

And people like this guy: https://bitcointalk.org/index.php?topic=417017.msg4672808#msg4672808

How about JUST powering the risers and not using the motherboard molex connectors? Would that be okay too? Or would powering both be the safer bet.

Thank you
llama

[bathrobehero]

+1

Also, nobody mentioned anything about the total power consumption the cards in these scenarios. I mean surely there must be a difference between using let's say 5 x 75w cards or using 5 x 250w cards.

[pontiacg5]

I also have an order coming in with a bunch of these ASRock H81 Pro BTC boards, and am slightly electrically dumb
I've been scouring the forums looking for reasons why some people advise NOT to use powered risers and some people say to use them at all times.

I personally run regular motherboards and *always* power my risers. But there seems to be a lot of confusion with these boards and the two on board molex connectors.
Can someone please explain why it's impossible for a card to burn out if use both the on board and the risers molex connectors?

I keep seeing things like this on the web, and this guy seems to have a farm: https://bitcointalk.org/index.php?topic=414751.msg4560094#msg4560094

EDIT: just found another thread with problems (same dude chimes in here from the link above, but the OP is the one with issues): http://www.overclock.net/t/1456912/2x-asrock-h81-pro-btc-fried-cant-be-swapped-mobo-wont-boot-help-mining-rig

And people like this guy: https://bitcointalk.org/index.php?topic=417017.msg4672808#msg4672808

How about JUST powering the risers and not using the motherboard molex connectors? Would that be okay too? Or would powering both be the safer bet.

Thank you
llama

I think you should listen to that guy(s) because they clearly know what they are doing. I mean these guys can't even get 6 gpus on that board made specially for mining  
They also seems to think you must not let your motherboard/gpu's run on two power supplies at once, also a fallacy. Regulated 12v is 12v, and I can't make that any easier for you. Would you like more pictures of my setups as proof?

Use powered risers, and preferably the USB version which have to be powered by design. A riser cable is a straight through device, there is nothing to short. If you can't use common sense to tell why, then I can't help you.

PCI-e x16 spec is allowed to pull no more than 75W from the pci-e slot.

[llamabucket]

Alright so after chatting with a few knowledgable people on IRC, I came to a conclusion:

If you power ALL risers with the SAME PSU that powers the motherboard, then there is NO need to use the molex connectors on the ASRock motherboard. Same applies when you have two PSUs per rig!

[pontiacg5]

Alright so after chatting with a few knowledgable people on IRC, I came to a conclusion:

If you power ALL risers with the SAME PSU that powers the motherboard, then there is NO need to use the molex connectors on the ASRock motherboard. Same applies when you have two PSUs per rig!

They don't even have to be on the same power supply, that's just dumb. Some gpus would get power from one power supply via the risers, then the rest via the 2nd power supply. So, if it's OK for a GPU, why would it make a difference for the motherboard???

I give up, can't believe people so "knowledgeable" can be so dense....

[llamabucket]

Are you 5 years old that you need to resort to insults like that?

The system can pull the power back through slot and through the motherboard traces again. Which is why people actually CUT the +12V wires if the risers are powered. So when you're running two PSU's, the one that's not connected to the motherboard may pull some power back through the slot down the riser.

Here's the example: http://forum.feathercoin.com/index.php/topic,2193.0.html

[pontiacg5]

Are you 5 years old that you need to resort to insults like that?

The system can pull the power back through slot and through the motherboard traces again. Which is why people actually CUT the +12V wires if the risers are powered. So when you're running two PSU's, the one that's not connected to the motherboard may pull some power back through the slot down the riser.

Here's the example: http://forum.feathercoin.com/index.php/topic,2193.0.html

I sure am, thanks for noticing!

The system can not "pull power back." Electricity follows the path of least resistance. If the traces/wires to the motherboard are still intact power will flow from both the motherboard and riser cables extrenal 12V INTO the card till the resistance of the motherboard traces shifts the load to the riser cable's supplemental 12V line nearly exclusively.

Besides, this just further proves my point. If the risers are already electrically isolated, it MATTERS NOT what power supply is feeding the riser cables.

I find it funny the very second post in the link you provided confirms what I pretty much just said though.

[llamabucket]

So we're back at square one then.

1) why are people having stuff shorting and frying with various combinations of PSUs, risers and motherboards
2) what is the best configuration running this ASrock motherboard? Connect ALL risers, molex on mobo and power to video cards to any cables on any number of power supplies? No risk?

[pontiacg5]

So we're back at square one then.

1) why are people having stuff shorting and frying with various combinations of PSUs, risers and motherboards
2) what is the best configuration running this ASrock motherboard? Connect ALL risers, molex on mobo and power to video cards to any cables on any number of power supplies? No risk?

1) People find new and creative ways to burn things up all the time. I can't tell you what they did, because most of them don't even know for sure. There are hundreds of threads and questions asking how to get 6 gpu rigs running, but I apparently have the only ones in existence? You don't often hear about things that go well, you hear about the screwups and mistakes.

2) Using usb riser cables, don't plug in the molex connections on the motherboard. Run the riser cards and GPUs however you want, so long as your power supplies are evenly loaded. If you use ribbon riser cables expect whatever comes your way with those cheap pieces.

[llamabucket]

Thanks for the suggestions.

I too have a few rigs running six 7950's successfully using good quality powered risers. I agree that you CAN do it, it just takes a little patience

As for this ASRock mobo, I will do like you suggest and what my gut feeling tells me to do: run all risers powered, but omit the molex connectors on the motherboard. I figure it should work the same as any other motherboard I've used in the past. I also wish I could use USB risers, but they are crazy expensive and when I've got 10 rigs to build next week, it can get pricey. I also just got a shipment of ~70 brand new and quality risers (30cm!) yesterday so I've got that ready to go.

[pontiacg5]

Thanks for the suggestions.

I too have a few rigs running six 7950's successfully using good quality powered risers. I agree that you CAN do it, it just takes a little patience

As for this ASRock mobo, I will do like you suggest and what my gut feeling tells me to do: run all risers powered, but omit the molex connectors on the motherboard. I figure it should work the same as any other motherboard I've used in the past. I also wish I could use USB risers, but they are crazy expensive and when I've got 10 rigs to build next week, it can get pricey. I also just got a shipment of ~70 brand new and quality risers (30cm!) yesterday so I've got that ready to go.

Good luck with the ribbon riser cables, especially the extra long ones.

Before you start using them, I would check that the 12V line is not shorted to the ground. The way they add supplemental power to those ribbon risers is not very clean, and if they miss by one (or two?) pin pitches you've got a dead short to ground that will certainly make smoke.