Bitcoin Forum

Hi all, I'm new to the forum but I've been mining sporadically for some time now.
I always mined with a regular pc, just for the fun of it, but I finally decided to build a proper rig to mine litecoins.

I bought this (from a gamer who was selling his hardware, so it was cheap):
MB: Asus Maximux V Extreme
VGA: 4x sapphire hd7970 ghz edition
1500W power supply
16Gb Ram, core i7 3.4Ghz cpu

I started mining with cgminer using initially some default setup and then going to experiment a bit. A 7970 sould be supposed to mine litecoins around 700Kh/s, however my trials with a single card setup never went above 460Kh/s.
If I try to add more cards the system slows down considerably (each card dropping as low as ~300Kh/s).
My best result was with this setup (referring to a single card setup):
DISPLAY=:0 ./cgminer --scrypt -o http://de1.suprnova.cc:8336 -u xxx.1 -p xxx --shaders 2048 --thread-concurrency 10240 -I 13 --gpu-engine 1000 --gpu-memclock 1750 --auto-fan -g 2

I tried both on linux and windows, with cgminer and reaper, and I always got similar results.

What can I do to get decent speed? Is there a problem with my setup? Am I missing something?

Thanks for your attention

if you arrange teamviewer/vnc I can take a look)

try --thread-concurrency 8192

why not just use join.me?

simple to use and doesn't require him to install anything :)

screen sharing is not possible without installing something.. more.. any activity on pc is not possible without installing something))

p.s.
join.me, isnt it paid service?

No, it is completely free :)

I tried every many values in the range 8192. The maximum stable value is 20240. After that it can't run.
Performance drops drastically after 16384, and is relatively good at lower values.

I doubt that this is a software problem (after trying all the possible parameter combinations it would be very strange that I missed the only one working). I forgot to say that I'm using cgminer 2.11.4 and 13.1  drivers.

Do you belive it could be hardware related? Is there some hardware magic that one must do when building such a setup?
I never installed more than a graphic card on a pc, and I find very strange that the overall performance is dropping after I start adding cards.

If nothing else works we can arrange a vnc session, however I would first try out DIY methods  ;D. Any suggestions? What should I try to do?

Are you running a 32 or 64 bit version of your OS? You might get memory capped per card or process. Take a look on memory usage while running mining and changing settings.

64 bit (both linux and windows 7).
I could easily install linux 32 bit for testing, do you think that the problem is related to that?

cgminer uses around 400Mb of ram (I don't know how much gpu ram, how do I test it?)
before starting cgminer:
with cgminer  running:

UPDATE:
I tried a sapphire HD7950 (borrowed) and I got ~580Kh/s at first try (I suppose I can go up with a bit of trial and error). The rest of the system is the same. How can it be that a 7950 is faster than a 7970?
I simply used --shaders 1792 -g1, and stock frequencies.
This is weird.

I could simply suppose that my 7970 (all 4 of them) are bad, or sapphire is such an ugly manufacturer, however something is unclear also with the 7950, If I try to plug two HD7950, and go with the same cgminer setup, the global hashrate is a bit lower! I expected double, but somewhere near 1100Kh/s is fine I suppose, but I get ~530 Kh/s... cgminer correctly see the two cards, but somehow it's able to get only less than half the power out of the two cards.
I'll open another thread for this problem

Please someone can explain me where I'm messing the configuration? Is there something specific I should know about multi-card setups?

I've had the same issue with two XFX 7970. Both only go about 370 kH/s no matter what I try. I have a gigabyte 7970 in another computer and it runs fine stock at about 680 kH/s. I've yet to find any fixes online  besides tweaking them till they work. Let me know if you get yours fixed (it'd be nice to double my hash rate on the machine  :P )

So do you think it's pure bad luck?
I can't believe that computers are magic... there should be a reason

is BIOS updated on the board? Chipset drivers for windows? All I could think of is a bottleneck is the system bus.

Everything is updated to last version. Also I'm using both linux and windows, since I'm testing (I'll chose the one who performs better), so it can't be related to driver. It can however be related to bios. I tried to play with the settings, but I'm no expert in changing the default voltages, so I didn't try that. If you have an advice (with careful explanation on what to change and where) I'll try to play with voltages.

I tried also with a pair of 7950, same brand, and I don't get the above problems. Despite getting a lot of HW errors, I can get to the proper hashrates (~1.2Mh/s with two cards, around 600 with a single card, more or less). If I want no HW errors I must lower the hashrate by half (using intensity 13 instead of 19, which is optimal for raw hashing). In this field Linux performs way better with a single card, while windows outperforms linux with a multi-card setup (this may depend on the configuration, I used default Xorg config, I'll try to get linux working in time).
A problem that I found is that it can't hash with thread concurrency greater than 10240, I don't know why. Maybe that is a hint of an hardware problem or a wrong bios setting?

I don't get why the system can't properly use the 7970s (or at least get in the range 550-650 Kh/s). Initially I thought it was related to some kind of powersaving on the pci express ports. I booted linux with pci_aspm=performance with no result. I also tried a similar setting in windows but it got me nowhere.

I want to get to the bottom of it. I cant just go on ebay and sell four 7970s. I got them cheap but still I paid with my money and I don't want to waste it.

P.S. since now I'm not a newbie anymore, should I repost it in a proper section? Is cross-posting allowed? Should I ask for deletion of this thread first?

well, on my 4000 series cards i couldnt get any more than 30khash each with cgminer. with reaper im getting 270 khash combined. so, i would try switching to reaper.

*coughs* Do you ever think about power, and the fact that two cards use more of it? *coughs*

Tune the card from AfterBurner, not from cgminer. 1750 memory clock is EXTREME. Make it 1550~1575. Also remove username and password from your post :)

That is kinda low I'm getting 400KH/s on a 7870 and 375 on the other (4x PCIe).  It actually runs better at a lower clock speed I do litecoin at 925Mhz and Bitcoin at 1225Mhz.  I'm also using "I 19" and not specifying clocks/shaders doing it through afterburner.

More than 1500W from the power supply? I doubt it. There is power in abundance. Do I have to pay attention to something? Other than plugging the cables in the card of course.

If I try I 19 it gives out too much HW errors. I tried reaper with similar results. I'll try afterburner, but I don't necessarily want to overclock the card, I simply posted the config that gave best results. The card has a 1Ghz stock core and 1.5Ghz stock ram, so my settings aren't that extreme.