Bitcoin Forum

Hi all,

I would like to create my first mining rig and, after I found so many ppl having issues with more than 3 cards, i would like to ask for some help:

Planned hardware:
Graphic card: 3x SAPPHIRE R9 280X 3GB GDDR5, when everything works fine, a 4th
Motherboard: ASRock 970 Extreme4 (but it has only 3x PCI slots, so which board can handle 4 cards?)


Questions:
1) I plan to run this via WLAN, using Teamviewer. Do you see any issues with that?
2) What motherboard should I use?  I didn't find one with 4x PCIe slots.
3) The card's spec are different on several sites, ranging from 250 to 750 Watts?
4) What power unit should I use, depending on the outcome above (3 or 4 cards)?
5) Can Windows 7 handle 4 graphic cards?
6) When running Windows 7, do I need to have dummy plugs for the cards?

Any help is appreciated, thanks for your time!

Any input plz?

1) works perfectly
2) asrock h81 pro BTC ( 6 slots no powered risers needed)
3) should be around 250-270
4) 1250w
5) yes
6) no

Hope that helps u forward

ASRock H81 Pro BTc is pretty good and It's available for 180 with free shipping on Amazon
https://www.amazon.com/dp/B00HEUIS2G?tag=ventallwu-20&camp=0&creative=0&linkCode=as4&creativeASIN=B00HEUIS2G&adid=043JVD2XQ7TJSZHFQFFM&

Thanks a lot for your input. I am ordering the following components:

card: 5x 280x.
motherboard: ASRock H18 Pro BTC
CPU: Intel® Celeron® Processor G1820 boxed
RAM: 4GB G.Skill DIMM 4 GB DDR3-1333
Risers: hard to get in Germany, buying powered Risers now, might take a week to get delivered :(.
HDD: I have one, about 3 years old, should be fine.

What PSU should I use? The cards will need 1250 Watts together.
Anything else I miss, except a rack?

4 280x on one 1250 is pushing it, no way to five

Ok, thanks... so maybe I should better go for 2 rigs, each 3 R9-280x, each with PSUs 850Watts?

You can use 2 psus in one rig  ;)

850w is enough for two 280x, not three. Two is pushing it, again. Use multiple PSUs

I did not find a description, how I need to work with two PSUs:

Do I need to somehow connect them or do they just work totally independant, one just cards + mainboard etc, the other just plain cards?

Will something break, if I turn on the PSUs in the wrong order for example?

You can make them work completely independent. To do that you have to short the green wire with any black on the atx connector (the one that goes to the mb). Or you can get an adapter to hook both of them directly to the mobo.

Nothing will brake if you turn them on in the wrong order, though the gpus that are connected to the second one might not be recognized. If the psu that just powers gpus is shut off the system will hang. It happened to one of my rigs that had plenty spare power on one psu and I use it to power some electronic projects. Quite a few times something went wrong and the psu shut off and all the gpus are still working.

Don't mix 2 psus in the same card.

Sorry, this I don't understand. Do you have a link to an adapter so I get an idea, what you mean please?

Your forum handle tells way too much about yourself.

1250 is fine for 4 280x. 5? Not without some serious undervolting. I have had a 5x 280x rig pull 1250W from the wall before, @ 1.01V, so it is possible. That's at the wall, which means the rig was only pulling 1100W from the PSU.

He did not mention that he would be undervolting. Four on a 1250 could be fine if he is not overclocking, if he is he would be operating close to the PSU limit (~250-350 watt/card). Undervolting would safely fit four on one 1250 psu. You can try for five on one 1250 undervolted, but I doubt its a good idea, especially recommending it to someone who is new. At least say *warning its dangerous to try this without a serious undervolt* . Its not really a good idea to push the wattage of PSUs to their maximum capacity anyways, and it will become less efficient over time.

I think, I go for 2 PSUs, as big PSUs are hard to get in my country.

The question is, what people mean about the V12 lines? What exactly do I need to check when ording a PSU?

And are there tests somewhere specificaly for this use case maybe?

something like that: http://litecoinminingparts.com/shop/cables/dual-psu-power-supply-adaptor-cable/

I don't know if the page is legit, just googled it.

And as for the 12v lines, some psu have several small, other have 1 big shared in between all the outputs. 1 big is better.

http://litecoinminingparts.com is legit, bought from him not long ago and going to buy more, it ships next day so...

My rigs have 3 r9 280x cards each. I have the sesonic gold 1050 psu. My 3 card rigs pull 940 watts at the wall, an 850 psu will not be big enough for 3 280 x cards.

Small update:
This rig currently runs with 2 cards (3rd is still not unpacked). The cards run at 707kH/s and 725kH/s. Details find here: http://www.das-hilfe-portal.de/technik/mining-rig-5x-r9-280x-7970-amd-ati/

every motherboard on market can use 4 video cards and even 5, but only a few ppl know how to get it working stable.

buying expensive motherboards is counter productive when a cheap mobo does the same job just fine.

I have a little farm of workers with 5x R9 280X on each (now I have ASUS R9280X-DC2(DC2T)-3GD5-V2, await for delivery of few boxes with Sapphire 280X Toxic)...

I'm use:
Windows 8.1 with AMD 13.12 drivers (if you use legal copy of W8 and enable Windows Update you can install drivers from it and no other setup - works fine)...
I'm prefer Intel 1155 socket (G1610/G1620 cpu's)...
Using motherboards ASrock H61DEL (just have before start busines with mining) and Asus Maximus IV Extreme (good off price from one shop and additional PCI-E power)...

Result of using of 3/4/5 GPU per rig is the that i know of RAM requirements: 4/6/6+ GB DDR3 (and 2 GB+ of swap) for cgminer memory mappings...
For PSU I'm use 1000W (real 1000W for 12V bus) per 3 GPU, 700-750W (also for 12V) for additional two...
Hint: read tests for PSU's before buy - many PSU can not hold voltage on +12V and on full load it can drop down to 10.9V and sometime lower... Some GPU cannot start at it, HDD can broke at 11.5 and lower of 12.5 and higher...
For M/B allowed extra power to PCI-E slots I'm not use powered risers, for other M/B I'm use powered...

For administration I'm use TeamViewer (when double NAT) or RAdmin (russian tool) (When I'm in local net with workers)...
Using CGMiner 3.7.0 (3.7.2 also works, but I'm prefer unufication, so 3.7.0... No other reason...) which starts from *.bat file from registry...

PS. 6x GPU works only on real new GPU like R9 290 and 290X with little easy tweaks (on Windows)... On Linux 6-7x R9 280X GPU's are work ok in my friends big farm...