Bitcoin Forum

Been lurking for a while and decided to build a litecoin miner. I purchased all new equipment for this purpose and do have the system running at the present time, but with only one card. When i add the second card my hash rates drop from 675 to 400 on the first card and the second card runs 375 hashes. My setup is :

I AM RUNNING GUIMINER---   I am not that good with computer scrypt , i had lots of problems on a ealier machine trying to configure Cgminer so i use this easier version.

Asus M5 A97 R2.0 Motherboard 1x16 slot and 1x1 slot.
2gigs of ram
Coolmax 850 watt poer supply
Two XFX R9-280x cards.

AMD APP SDK v2
AMD Catalyst ( don't know which version but was the newest i would imagine)


Any help would be appreciated, i just can't seem to get it to work very fast with both cards in.


Thank you

Anyone possibly know why?

GUI has overheads. Even if you fix the decreased hashrates you'd be much better off with CGminer or BFGminer.

https://litecoin.info/Mining_hardware_comparison

Has all the configs you'd need for your cards.

If you need a hand setting up your cgminer conf file I don't mind lending a hand. I don't use CGminer much now that I use Cudaminer, but I had it running just fine. Honestly, you'd be much better off.

Thanks for the reply nullu, I don't really know where to get cgminer at and which version to use. I also dont know how to set up two cards in the bat file. Any help would be appreciated.

Thanks

Probably dumb to mention it, but also make sure your cards aren't in crossfire. I am looking at building something like this as well, how much-ish did it run you?

Try this one with cgminer, create a .txt file and write this line:

cgminer --scrypt -o "server:port" -u "yourusername" -p "yourpassword" --thread-concurrency 8192 -g 2 -w 256 -I 13

Remove the "" and put your details inside, then rename the file as a .bat file.

It gives me around 720KHash/s stable with my rig of R9 280x with a temp of 60-65° for each card (with raisers).

I made sure the cards are not in crossfire mode and the system was $900 to build. Portatech was switching out the 7950 cards for the same price with XFX R9-280x cards. Another wierd thing is the second card hashes at 565 while the main card hashest at 676. The proccessor use on the second card is very up and down..looks like a heartrate monitor at the hospital. It goes to 99% then dumps to 65% and continues this all the while at a one second interval.

that's a heat issue that's making the card retune the GPU speed.  get a lot more fans going in there and see if your hash rate stabilises. 

try a different pool. The hash blocks you're working on might be so small your CPU is having trouble keeping up with the priority postings per GPU. Try middlepool for a few minutes. They send out 512 blocks and it might act differently.

Thanks, yes gpu #2 is running 79 degrees and number one is 60. I need to get some risers, whers the best place to get them?

Does it matter much that i only have 2gigs of ram? Seems like it doesnt but i thought that was why it was throttling back on the card.

I also have another comp running one msi 6950 with guiminer and that hashes a constant 446.

I downloaded cgminer 3.7.2 and am attempting to write a .bat file. Could someone show me an example of how it would look from start to finish with the setup i have (two r9-280x cards)? I would really appreciate it and then i could just make one like it with the address , worker and password of my own.

This may sound crazy, but so be it. A friend of mine ran in to the EXACT same problem. When he went from 2 gigs of RAM to 4 gigs, it solved the problem.

He was trying to cheap out on the build. Started with 1 gig, it wouldn't run worth a damn. Went to 2 gigs and it ran 1 card fine, but the same issues as yourself when trying to run 2 cards.

I just confirmed all of this with him, so if your issues persist, add memory. And, as a side note, if it fixes the problem, please post a follow-up reply.

Oldgascan