From e62cb4ee123ed9ce1a94e2f9b84b85e9891bcc06 Mon Sep 17 00:00:00 2001 From: Con Kolivas Date: Fri, 5 Apr 2013 10:32:52 +1100 Subject: [PATCH] Add example 7970 tuning for scrypt in readme. --- SCRYPT-README | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 67 insertions(+) diff --git a/SCRYPT-README b/SCRYPT-README index 734d3990..36e57e2e 100644 --- a/SCRYPT-README +++ b/SCRYPT-README @@ -166,7 +166,74 @@ For example, a 7970 running with the following settings: was using 305W! --- +TUNING AN AMD RADEON 7970 +Example tuning a 7970 for Scrypt mining: +On linux run this command: +export GPU_MAX_ALLOC_PERCENT=100 +or on windows this: +setx GPU_MAX_ALLOC_PERCENT 100 +in the same console/bash/dos prompt/bat file/whatever you want to call it, +before running cgminer. + +First, find the highest thread concurrency that you can start it at. They should +all start at 8192 but some will go up to 3 times that. Don't go too high on the +intensity while testing and don't change gpu threads. If you cannot go above +8192, don't fret as you can still get a high hashrate. + +Delete any .bin files so you're starting from scratch and see what bins get +generated. + +First try without any thread concurrency or even shaders, as cgminer will try to +find an optimal value +cgminer -I 13 + +If that starts mining, see what bin was generated, it is likely the largest +meaningful TC you can set. +Starting it on mine I get: +scrypt130302Tahitiglg2tc22392w64l8.bin + +See tc22392 that's telling you what thread concurrency it was. It should start +without TC parameters, but you never know. So if it doesn't, start with +--thread-concurrency 8192 and add 2048 to it at a time till you find the highest +value it will start successfully at. + +Then start overclocking the eyeballs off your memory, as 7970s are exquisitely +sensitive to memory speed and amazingly overclockable but please make sure it +keeps adequately cooled with --auto-fan! Do it while it's running from the GPU +menu. Go up by 25 at a time every 30 seconds or so until your GPU crashes. Then +reboot and start it 25 lower as a rough start. Mine runs stable at 1900 memory +without overvolting. Overvolting is the only thing that can actually damage your +GPU so I wouldn't recommend it at all. + +Then once you find the maximum memory clock speed, you need to find the sweet +spot engine clock speed that matches it. It's a fine line where one more MHz +will make the hashrate drop by 20%. It's somewhere in the .57 - 0.6 ratio range. +Start your engine clock speed at half your memory clock speed and then increase +it by 5 at a time. The hashrate should climb a little each rise in engine speed +and then suddenly drop above a certain value. Decrease it by 1 then until you +find it climbs dramatically. If your engine clock speed cannot get that high +without crashing the GPU, you will have to use a lower memclock. + +Then, and only then, bother trying to increase intensity further. + +My final settings were: +--gpu-engine 1157 --gpu-memclock 1900 -I 20 +for a hashrate of 725kH. + +Note I did not bother setting a thread concurrency. Once you have the magic +endpoint, look at what tc was chosen by the bin file generated and then hard +code that in next time (eg --thread-concurrency 22336) as slight changes in +thread concurrency will happen every time if you don't specify one, and the tc +to clock ratios are critical! + +Good luck, and if this doesn't work for you, well same old magic discussion +applies, I cannot debug every hardware combo out there. + +Your numbers will be your numbers depending on your hardware combination and OS, +so don't expect to get exactly the same results! + +--- While BTC donations are preferred, if you wish to donate to the author, Con Kolivas, in LTC, please submit your donations to: