XFX Black Edition R9 280x (4 cards on 1 motherboard) Having some issues.

[HashHound]

Hey everyone! I recently built my first scrypt mining rig, and I'm having trouble getting the thing to kick out anywhere near the numbers some of you are getting with your r9 280x's.

I've heard some bad things about XFX cards on other forums, but I'd like some advice from you guys. I have 4 of these cards (http://www.newegg.com/Product/Product.aspx?Item=N82E16814150690)

I've tried multiple different settings on cgminer, but nothing seems to work.  Any advice here would be awesome.

I had my machine running 2 of the cards at ~700kh/s each, while I was waiting for my risers to ship. Hopefully my risers aren't messed up or something.

Anyways, this thing has given me so many problems, but I really want to see it running at full speed.

Thanks in advance.

[1713937434]

1713937434

[HashHound]

Forgot to add, I'm using two 750 watt power supplies, and the motherboard is an ASUS M5A97 (http://www.newegg.com/Product/Product.aspx?Item=N82E16813131873).  Also, I'm running 8gb of ram on the system.

[HashHound]

I'm currently using these settings.

-I 13 -w 256 --thread-concurrency 8192 -g 2 --gpu-engine 1040 --gpu-memclock 1500

With these settings, 2 cards run at 100% speed and 2 cards are running at like 5% speed.

I tried to put in --powertune 20 and this briefly enables 3 cards to run at 100% speed, then my machine crashes.

I realize there is no one replying here, but I don't know where else to go for information.

Help please! =o

[HashHound]

It's probably not so much your settings but the power distribution.
I have 4 x 290X running on a 1500W and had to try all kinds of PCI-E connector combinations on those cards to keep it running without crashing when 100%.
Those R9 cards pull a lot of power so make sure you don't put every card on one rail of your PSU.

My PSU has 5 rails and each has 2 PCI-E plugs on it, I had to use all 5 for the 4 cards.
Example:
Connector 1 of rail 1 in card 1 8-pin PCI-E
Connector 2 of rail 1 in card 2 6-pin PCI-E
Connector 1 of rail 2 in card 2 8-pin PCI-E
Connector 2 of rail 2 in card 1 6-pin PCI-E
Connector 1 of rail 3 in card 3 8-pin PCI-E
...and so on, it's not an exact science because I had to try some other combinations too, all of this also depending on your PSU quality.

Maybe that's the issue for you too

Thanks for the reply. I'm pretty sure each card has it's own rail. I'm using a couple modular PSUs. However, I do have the powered risers 2 risers per rail? Should they also have their own?

Is there a more efficient way to divide up the power I'm using? Maybe put 3 cards on one PSU and then the motherboard, hard drive, risers, and main GPU on the other PSU..?

Also, do I need to do anything with the main power line from the PSU that is NOT powering the motherboard?

I kinda jumped into all this without knowing too much about power/voltage.  That probably wasn't the brightest idea.

Thanks again.

[HashHound]

So it looks like I didn't have enough power between the 2 power supply units to power 4 cards.

I'm running 3 cards just fine at ~700 Kh/s each. Now what to do with this other r9 280x..? Maybe I should upgrade one of the 750 watt PSUs.

Maybe I'm just bad at setting all this up and the 2 PSUs I have will do just fine for 4 cards.  Anyways, it's time for me to stop messing with it for the night.

[MoneyMorpheus]

I can't get an ASUS mobo working with risers, even not with powered full 16x ones, don't know why but my 4 x 290X have to be connected directly to the mobo PCI-E slot or they don't get recognized.

I only have asus amd mobos and I'm using all of them with unpowered risers fine, perhaps you got bad risers? I bought cheap chinese ones (10 usd) and one of 7 was DOA.

As for OP you are a bit tight, more info on the psu rails will be helpfull. A bit of undervolting might do the trick 

[HashHound]

You shouldn't connect the two PCI-E of the same modular PSU rail to one card, that is also somewhere stated in the manual of the GPU.
So each power rail is connected to 2 GPU cards, 8-pin to the first GPU, 6-pin to the second GPU.

I tried this, the machine was more stable when I had 1 cable per card.

I've tried so many different setups with my power supplies. (http://www.newegg.com/Product/Product.aspx?gclid=CPLK1P6f2bwCFecRMwodKlYAhQ&Item=N82E16817182264&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Power+Supplies-_-N82E16817182264&ef_id=UuYUTwAAAfbx9LV1:20140219223501:s) Like I said, the most stable set up was with 1 card on the main PSU and 2 cards on the 2nd PSU, all cards were on their own individual rail.  My PSU manual says nothing about how to setup multiple PCI-e video cards.

Sorry for bailing on this post, I was out of town.

[grauwolfe]

I've had similar problems (but with different cards in on PC).
Try set parameters directly for each GPU:
-I 13,13,13,13 -w 256 --thread-concurrency 8192,8192,8192,8192 -g 2 --gpu-engine 1040,1040,1040,1040 --gpu-memclock 1500,1500,1500,1500

and, after launch, check with GPU-Z or MSI AfterBurner gpu voltage and memclock for each videocard.
For me, cgminer often ignores frequency set by commandline so i had to set it directly from afterburner.

For my XFX R280x black, those settings do 680-740 kH/s: --scrypt -I 13 -g 2 --lookup-gap 2 --thread-concurrency 8192 -w 512 --gpu-powertune -20 --gpu-engine=1030 --gpu-memclock=1500 --no-submit-stale

Forgot to add: 750w PSU probable not enough. 650w is minimum to power motherboard/hdd+ one 280x - when I used 500w psu for some time, my pc reboots several times a day.