Low Litecoin hashrates on 5870s

[Zithras]

Previously, I have been mining Bitcoins with GUIMiner with no problem, and am trying to switch over to Litecoin mining using CGMiner.
For some reason, scrypt seems to be failing horribly, and I'm not sure why.

I have 3 5870s on this computer and am expecting a rate of about 1000 khash/sec

Instead, whenever I use the --scrypt flag, I seem to get about 5 kH per card, giving me a rate of 15khash....needless to say, this is pretty much unusable.
If I don't, I get 1000Mhash, but then, of course, all my blocks are rejected, because I'm not actually mining lightcoins at that point...
I'm pretty sure I am missing something obvious, but have no idea what it could be.

command line:
cgminer.exe --scrypt -o http://litecoinpool.org:9332/ -u X -p X --shaders 1600 -I 2,2,2
tried intensities ranging from 2-13.  (Tried 19 too, but that causes an instant computer crash)

Bitcoin mining, of course, still works fine at over 1k Mhash/sec with:
cgminer.exe -o http://stratum.bitcoin.cz:3333/ -u X -p X --shaders 1600 -I 2,2,2 (or higher intensities for when i don't need the computer)

Arrrgh!
Any help or advice would be greatly appreciated.

Update: reading some more, it seems that some people were getting this problem when switching over from CGMiner 2.6.1(4) to 2.7 when BAMT upgraded to 0.5.c
Considering that cgminer is now on 2.11, surely there's some kind of fix by now?  I couldn't find anyinformation on what exactly the problem is, or how to fix it...and ideas?
update2: Used MinGW to build older versions...2.6.4 has the same problem, and so does 2.6.1 - back to the drawing board. 

It's definitely a scrypt problem, since I can mine bitcoins just fine.

TLDR version: WHYYYY am I getting 15khash while mining litecoins on 3x5870s?  It should really be 1000ish.  Bitcoin mining works fine.  Want to mine litecoins, but getting annoyed.

[wndrbr3d]

What platform? DERP, just saw GUIMiner so I assume Windows.

Here's what I'm using on CentOS 6.4 with 13.2 Beta 7 Drivers:

Code:

./cgminer --scrypt -o http://pool:9332 -u username -p password --worksize 256 --shaders 1600 --intensity 11 -g 1

I'm getting about 320khash/sec from my 5870

[Zithras]

Windows 7 Ultimate x64

Using your parameters, namely
cgminer.exe --scrypt -o http://litecoinpool.org:9332/ -u x -p x --worksize 256 -g 1 --shaders 1600 -I 11

I am now getting 450 kHash/sec (about 150 per card)

Definitely progress from 15 kHash/sec, but certainly nowhere what I *should* be getting - about 1/3-1/2 of what I should be getting, in fact (since youre getting 320 from your single card...)

I'm using 12.8 and 12.10 drivers - I believe the display driver is 12.10, but i didnt update the catalyst software from 12.8 since 12.10 was bugging

[wndrbr3d]

Play with the Intensity. On Windows I was able to get it up to 18 for max performance, but it varies between drivers and cards.

[Zithras]

Spent most of last night running through setting again...here's what I found

-I : higher intensity gives higher results, as expected, but runs into heavy diminishing returns above 14-15 or so.  Before that, huge gains are possible, after that, you might get 1 kHash per level.  Intensity below 10 or so gives me a pathetic 5 kHash or so per card, and intensity between 10-14 or so gives me 100 kHash or so on cards 2 and 3, but 5 on card 1.  Intensity goes up to 20, and is usable at that setting, but any additional activity other than closing the lightcoin miner is extremely slow and often leads to crashing

--worksize: adjusting this doesnt result in much gain or loss, myabe 10-30 kHashes/sec, but its still worth looking at.  for lower intensities, 60 seems optimal.  As intensity goes above 14ish, optimal worksize changes to 256.  I also tried 60, 128, 256, 512

-g: Little to no change running 1 or 2 threads per card for intensities 1-12.  Intensity 13+ crashes the computer when this is set to anything but 1

--shaders: based on type of card, did not touch.  I am using 3 5870s, so 1600 is correct

The final maximum efficiency command line I found was:
cgminer.exe --scrypt -o http://litecoinpool.org:9332/ -u Zithras.1 -p x --worksize 256 -g 1 --shaders 1600 -I 20,20,20

This gives all 3 cards a slowly climbing rate, maxing and holding at about 303 kHash/card after about a minute of runtime.

Overall, I'm getting about 910 Khash out of this 3-card setup.  Usable, but lamentably well below other reports of 340 kHash/card  about a 12% loss per card, in fact.  Anyone have any other ideas, or do I just have bad cards?
using 3x ATI Radeon 5870 XFX HD-587A-ZNF9 Details: http://www.newegg.com/Product/Product.aspx?Item=N82E16814150443

Many thanks to wndrbr3d for the help thus far

[wndrbr3d]

Drivers have a lot of play in performance both reported previously and currently reachable. The results reported on the wiki from 12.6 will be +/- 15% from what you'll probably get from 13.2

I wouldn't read too much into it and consider your accomplishments a win.

Additionally, OC your video memory a little and that should squeeze some more juice from the cards.

[c4n10]

You won't see 1,000 KH/s with intensity setting of 2...

I get ~350 KH/s with a single Gigabyte 5870 SuperOC using the following settings for scrypt:

Code:

cgminer --scrypt -o http://url.com:port -u username -p password --thread-concurrency 8192 -I 18 -g 1 -w 256 --gpu-engine 850 --gpu-memclock 1290 --gpu-vddc 1.175 --gpu-fan 100

[ChanceCoats123]

I agree with what has been said. Intensity needs to go up for sure. I get ~310khash with a 5850. You should be 350+ with that 5870 on comparable settings.

[funkenschuster]

try reaper v13!

[juve4v]

My 5870 does 400 Mh/s with reaper v.13   clocked to  900/1264/1163  settings: --tc 8000, -w 256 --st 10 -I 20 .

[Zithras]

Looks like the best I'm going to get with cgminer and Catalyst 12.8/10 is 1080 Khash (across 3 cards) with

cgminer.exe --scrypt -o http://litecoinpool.org:9332/ -u x -p x --worksize 256 -g 1 --shaders 1600 -I 17,17,17

Anything higher than 17 shows as being better locally, put actually slows down the average reported in the pool stats.

Oddly enough, even though the pool stats are reporting 1080 Khash avg, cgminer is itself reporting 903 across the cards...

Still, assuming the pool figures are correct, 360/card is right in there range of where I should be!  Yay!

No idea why cgminer is reporting it so much lower internally.

[gnarcoinguy]

You might try the "--thread-concurrency" setting instead of "--shaders" with cgminer. It overrides the shaders setting if there is one and can lead to better performance.  According to the man page itself for cgminer, the 5xxx series do best with 5x the number of shaders as a setting.  I have dual 5850s and I use 7168 and get 300khash/s each card, and thats running at stock 725Mhz.  It seemed to be the best performance in my tests (1440 shaders in a 5850 * 5 = 7168). However overclocked I can get 350khash/s per card but I choose not to OC it most of the time.

I use this for my 5850s, give it a shot:

cgminer.exe --scrypt -o  http://url -u user -p password --thread-concurrency 7168 -I 18 -g 1 -w 256 --auto-fan --temp-target 66 --temp-overheat 71

Or since you have 5870s with 1600 shaders ( I think ) , try this instead:

cgminer.exe --scrypt -o  http://url -u user -p password --thread-concurrency 8000 -I 18 -g 1 -w 256 --auto-fan --temp-target 66 --temp-overheat 71

And perhaps adjust the intensity level down a notch or two for initial testing.  I find testing settings at intensity 12 allows the desktop to still be usable, and at the same time gives you a good baseline for what works.  When you get the highest hash rate you can at intensity 12, then its time to start bumping it up (usually).

[Zithras]

Pool hashrate figures were incorrect must have hit them at a spike- I'm actually getting 860-900 khash/sec, with the client reporting 895-905 - sad, but makes more sense.  Still, 860 is a far cry from 9, which is where I was when this thread started, so at least I can now mine litecoin if it becomes much more profitable than bitcoin again (15-20% or so seems to be the likely breakpoint, since my cards aren't quite as efficient at mining litecoin - didn't get the ideal 1mhash-1khash equivalency)

using --shaders as suggested doesnt really do anything for hashrate (maybe adds 3 khash, if that), but DOES seem to keep the system much more stable so shaders it is!  I've played with other intensities, and can go up to 20, but the gain between 18 and 20 is extremely marginal (15 khash or less), and seems to be offset by increased stale shares and the occasional dead-reporting card after several hours, so I'm at all sure anything over 18 is actually a net gain.

[hmmmstrange]

5850 gets me 401.9Kh/s
cgminer.exe --scrypt -o 127.0.0.1:9332 -u xxx -p xxx --shaders 1440 --gpu-fan 72 --gpu-engine 950 --gpu-memclock 1100 -I 19 -g 1

This is pretty close to my cards max overclock. Runs at 61.0C