Bitcoin Forum

Hi all,

I'm building my first rig with 4 x Sapphire AMD Radeon HD 7970 3GB GDDR5 OC.

Do I  need to use the riser cable with or without power?

Thanks for your feedback!

Depends how many GPUs your motherboard is designed to handle. Most boards aren't designed with more than two GPUs in mind. Powered risers are your safest bet regardless.

I have this motherboard = GIGABYTE GA-990FXA-UD5

You will need a powered riser for at least the fourth card, I would suggest at least two just to be safe, though. 7970's are power hungry.

Thanks for the feedback AzureEngineer!!

 ;D

Anyone have a link for a good powered riser?

www.cablesaurus.com

www.buyahash.com


I have an order with Cablesaurus (they still have not been delivered) I ordered about a week and a half ago.

The Owner of BuyAHash responded to me on Reddit:

http://www.reddit.com/r/litecoin/comments/1dlpfs/cheap_and_easy_risers/c9syqb8?context=3

why not use a riser and use power adapter instead?  Much cheaper route I think

I got an order of 5 off of E-Bay (from Hong Kong, though, so be prepared to wait) in a single listing for ~$25.

They shipped out the day I ordered along with tracking.

I'd like to tack onto this thread!

I also offer both types powered risers at Cryptocables.com (http://Cryptocables.com) if anyone is looking for any! I am based in the US, and have flat rate shipping domestically and internationally. Additionally, I also include free Pop Rocks candy with every order :o)

If you have any questions please don't hesitate to contact me!

Can i use all x16 by x16 riser cable for all slots? because the there is one x4 and one x8 and two x16.

I think you can use 1x to 16x cables for all cards.  At least I've seen many rigs with this setup. someone please tell me if I'm wrong because I ordered a 10x lot of 1x to 16x cables.

1x to x16 cables are fine for all cards

Actually, I have the exactly the same setup (mobo and cards) running with 4 cards, without powered risers. Has been running stable for weeks (mining litecoin), no problem so far. I have just mailed Gigabyte customer support if its ok to plug in a fifth card... We keep you posted about the results, hehe.

Do you have a picture to share with all of us :)

With 4 cards do you have to do any kind of special configuration? or just plug it into the motherboard with the riser cable?

What OS are you running?

You don't need special configuration, just plug in the risers. But not all combinations of PCIe slots work. Was a bit of trial and error until all cards got recognized.

OS is Win 7.

Will post some pictures later!

Thanks Sophokles!

It's awesome!!

Where did you get the hardware for that open air rig?

Very nice design, well built and looks to be very good at cooling. If your using windows I wouldn't recommend a fifth graphics card because they have problems after four but other than that, good job and best of luck!

Thanks! I actually designed it myself  ;). The aluminum profiles were ordered cut to the required lengths (4,50€/m). Including nuts, bolts, angular connectors and the black stopper caps, it was about 70€.

Thanks! I also got the fifth card running now. Didn't work with 13.1 drivers (code 43 for one card), but with 12.6 all working. Seems like the older drivers are more likely to be ok with more than four cards.

I think I'm going to post some images in the 'Show us your rig'-Thread now  :)

Anyone know a seller in Europe?

Finally got my 4 * 7970 up and running!!

https://i.imgur.com/elsSe16.jpg

Well, I suppose power would be better! :)

Just google 'aluminum profiles' in your local language. This stuff is readily available. Even on ebay.

nice rig

Nice job! Are the big fans blowing downwards? Maybe you want them to suck air upwards, in the normal direction the heat would go. That could optimize airflow and temperatures.

nice rigs

Thanks for the feedback Sophokles!! I've put it on the side now so it'll blow hot air out the window.

 ::) ??? 8)

Power is better

Sophokles,
Excellent Setup, neat and tidy very well designed. Did you try the 13.5 Beta drivers, they are very stable for me even better than 13.4

Back to the issue of the PCI-e riser cables, as i can understand you are currently using 1x risers (non powered) for all five GPUs, it that correct?
i have been reading tons about the subject and there is lots of conflicting views out there, so i would prefer the experience of a working setup.

What PSU you are using that provides 10 x 8 PCIe power connectors?

I have 4 non-powered risers. And one powered for the fifth. Working fine until now, even with litecoins, which brings extra load on the hardware. (Was too chicken to add a fifth without powered riser. Just read massnerder's thread before about his rig catching fire).

The PSU is an Enermax Platimaxx 1500. Real beauty. Comes with even 6x double 8 PCIe connectors. And a lot more stuff. Even certified to run 24/7 at 100% load, at 40 °C ambient temperature. Plus 93% efficiency. Comes at a price, but definitely worth it!

Thanks for the quick reply.
I am still not buying the need for powered riser with the 7970s, moderately OCed at stock voltage (1.17x v) each card burns approx 270W-280W (at wall socket measurement), since each card is feed with dual 8-pin PCIe power, that's 300W total which makes power draw from the mobo a minimal amount unless the card by design prefers to draw from the mobo than the PCIe power input.

Yes, exactly. Unless someone takes the time to measure it, we will not know how much power the 7970 draw from the PCIe slot. And so we cannot say if the mobo can safely provide 5 times that. I inquired with the mobo manufacturer, and they advised against running more than 3 high-end cards on that one.

So, try it if you feel lucky  ;). But the risk is burning up your board, or even setting your place on fire when it happens in your absence. I'd rather not risk it...

No One can claim to be that lucky  :)
check this post, have some figures on the PCIe slot current but for bitcoin mining
https://bitcointalk.org/index.php?topic=199706.msg2082941#msg2082941

So, finally someone took the trouble of making and publishing measurements! If the 7970 actually only draws 0.9 A, then 5 of them would be no problem in terms if PCIe power draw. Or even several  more.

Wow nice setup!

So i guess its time for me to bounce the question back to you, "Do you feel lucky?"  ;) just kidding.

The only troubling part is about the card's memory drawing its power from the PCIe solt, that what makes all the difference between the Bitcoin and Litecoin mining. So i guess it will come down to your Thread Concurrency setting, too high TC will result in more memory used hence more power draw.
You can always check the mobo and power connectors to see if it is running hot as they described, not sure how we can do that effectivly with all the head blowing from the cards