Underclocking my GPU made my hash rate faster why?
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Hi
wondering if anyone can explain to me how come after i under clock my cards, it made my Hash rates faster …
my cards are 280x Gigabyte default clock is 1100
but when i down it to 1050
my 2 cards when from 600 to 680 and the other card when from 650 to 730…
can anyone tell me why? should i try under volt it as well? what is a safe under voting %?
thanks
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What sorcery is this?
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[url=http://forum.feathercoin.com/index.php/topic,5326.0.html]http://forum.feathercoin.com/index.php/topic,5326.0.html[/url]
search a little
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yeah i saw your post too, before when i was trying to find the answer, but just would like to understand the reason behind, why it would be faster with slower clock speed :( sorry iam new to this, so i would like to understand the reason behind it :)
by the way i see you under volted your card by 20% is that harmful to the CArd?? thanks
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they have been running fine for a week now. Seems to be good.
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While the absolute clock speed of course influences the hash rate you can get, the ratio of GPU engine clock to GPU memory clock is more important.
There seems to be a peak in hash rate when setting the gpunclock to 0.5 - 0.6 of the memory clock.
Tuning suggestion:
Set your GPU engine clock to 50% of the GPU men clock and increase by 5Mhz steps as long as the hash rate increases. At a given point the hash rate will start to decrease. then reduce the GPU engine clock in 1 MHz steps, until you find the best hash.
(Taken from README.scrypt of the bfgminer project on github)It takes some time, but worked very well for me
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If you were to graph every hash rate to gpu/mem ratio you would find some interesting results. The scaling is not and never will be linear for scrypt, this is because both the vram and gpu cores are being used. Instead there is a balancing act between gpu core clock and memory speed, if either is too fast or slow the hash rate can drop off fast.
