LTC mining question

G

Gorilla

Supreme [H]ardness
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Sep 14, 2007
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Why would two cards of the same model with very similar khash rates have a big difference in shares accepted? I have two 7850s. The first is clocked at 1050/1320 and the second is clocked at 1000/1320. I started them both last night at the same time. The first is getting around 356 khash/s and the second is getting around 340 khash/s which makes sense given the difference in gpu core clock. But, the first has had 3739 shares accepted and the second has had only 2940 shares accepted with 14 stales. That's a pretty big difference that doesn't seem to be explained by the 5% clock speed difference.

They are both using the same default 7850 (low usage) settings in GUIMiner.


I did just realize that I set one to use usa.wemineltc.com and the second one to use world.wemineltc.com. Could that cause such a disparity?


Also, how does worker max difficulty work?
 
Max difficulty works in how fast your card goes for new blocks. my 7970 is set to 192 max difficulty which is a sweet spot for the 7970's. I dont think you would set yours above 128 or default at 64.


Snipet from "WeMineLTC FAQ" regarding difficulty settings
Setting max difficulty too low on a fast card will result in your card retrieving work from the server too often and the time it is getting new work is wasted time that it could be crunching higher diff shares. We recommend setting difficulty max to 192 for 7950/7970, 512 for dual 7970/7950 and 600 for tripple 7970/7950. Difficulty higher than 600 should not be needed, if you think you need it you can create a ticket on the forums issue tracker. Experiment to see what works best for your card. If you mine with a CPU, set suggested difficulty very low.
 
Thanks for the info, it seems I had the max difficulty way to high for my cards.


I still don't understand the difference between the share accepted rate between my cards. I stopped them both, changed the second 7850 over to usa.wemineltc.com and started them both back up and now the first card has 63 shares accepted but the second card has 214 shares accepted even though the first card has a higher khash/s rate.

Edit: now card 2 is at 359 shares accepted and card 1 is at 122. I don't get it, why is card 2 producing 3 times as many shares as card 1.
 
Last edited:
I have one better for you. My 6970 card, if I clock it at 955 it pushes out 515-530Kh/s, if I clock it at only 950, it drops to 430Kh/s, how stupid is that? I can also clock the memory from 1450-1500 and it makes no difference whatsoever and If I clock the core above 955, I gain almost nothing as well. There definitely seems to be a "sweet spot" for most cards I've found, it's just a matter of taking the time to find it.
 
Pitbully said:
I have one better for you. My 6970 card, if I clock it at 955 it pushes out 515-530Kh/s, if I clock it at only 950, it drops to 430Kh/s, how stupid is that? I can also clock the memory from 1450-1500 and it makes no difference whatsoever and If I clock the core above 955, I gain almost nothing as well. There definitely seems to be a "sweet spot" for most cards I've found, it's just a matter of taking the time to find it.
Click to expand...

It's more about ratios that max clocks for GPU/RAM. I know for a fact that i *LOSE* k/hash when I increase one without increasing the other.

5770: .75 GPU : 1 RAM
58XX: .85 GPU / 1 RAM
69XX: .85 GPU / 1 RAM
R280x: .7GPU / 1 RAM

Seems to get me the best performance for me.
 
JapaneseGorilla said:
Thanks for the info, it seems I had the max difficulty way to high for my cards.


I still don't understand the difference between the share accepted rate between my cards. I stopped them both, changed the second 7850 over to usa.wemineltc.com and started them both back up and now the first card has 63 shares accepted but the second card has 214 shares accepted even though the first card has a higher khash/s rate.

Edit: now card 2 is at 359 shares accepted and card 1 is at 122. I don't get it, why is card 2 producing 3 times as many shares as card 1.
Click to expand...

screenshot your CGminer
 
It gives you a lot more info on what is being done (and if there are any HW errors).

Work is not equal to number of shares done, it is equal to the difficulty weighted number of shares. Higher difficulty shares are worth more, so it is possible that your two cards are actually doing the same work.

With CGMiner, it has a WU number which takes difficulty into account.
 
one card could also be partially unstable and be getting high hardware errors. Try increasing their max power in CCC
 
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