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@@ -51,9 +51,9 @@ disastrous with scrypt because it CAN run out of ram. High intensities
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start writing over the same ram and it is highly dependent on the GPU, but they
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can start actually DECREASING your hashrate, or even worse, start producing
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garbage with HW errors skyrocketing. Note that if you do NOT specify an
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-intensity, cgminer uses dynamic mode which is designed to minimise the harm
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+intensity, BFGMiner uses dynamic mode which is designed to minimise the harm
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to a running desktop and performance WILL be poor. The lower limit to intensity
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-with scrypt is usually 8 and cgminer will prevent it going too low.
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+with scrypt is usually 8 and BFGMiner will prevent it going too low.
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SUMMARY: Setting this for reasonable hashrates is mandatory.
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--shaders XXX
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@@ -62,7 +62,7 @@ is a new option where you tell BFGMiner how many shaders your GPU has. This
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helps BFGMiner try to choose some meaningful baseline parameters. Use this table
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below to determine how many shaders your GPU has, and note that there are some
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variants of these cards, and Nvidia shaders are much much lower and virtually
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-pointless trying to mine on. If this is not set, cgminer will query the
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+pointless trying to mine on. If this is not set, BFGMiner will query the
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device for how much memory it supports and will try to set a value based on
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that.
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SUMMARY: This will get you started but fine tuning for optimal performance is
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@@ -162,7 +162,71 @@ For example, a 7970 running with the following settings:
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was using 305W!
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---
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+TUNING AN AMD RADEON 7970
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+Example tuning a 7970 for Scrypt mining:
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+On Linux run this command:
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+export GPU_MAX_ALLOC_PERCENT=100
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+or on Windows this:
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+setx GPU_MAX_ALLOC_PERCENT 100
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+in the same console/bash/dos prompt/bat file/whatever you want to call it,
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+before running BFGMiner.
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+
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+First, find the highest thread concurrency that you can start it at. They should
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+all start at 8192 but some will go up to 3 times that. Don't go too high on the
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+intensity while testing and don't change gpu threads. If you cannot go above
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+8192, don't fret as you can still get a high hashrate.
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+
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+Delete any .bin files so you're starting from scratch and see what bins get
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+generated.
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+
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+First try without any thread concurrency or even shaders, as BFGMiner will try to
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+find an optimal value
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+bfgminer -I 13
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+
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+If that starts mining, see what bin was generated, it is likely the largest
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+meaningful TC you can set.
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+Starting it on mine I get:
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+scrypt130302Tahitiglg2tc22392w64l8.bin
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+
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+See tc22392 that's telling you what thread concurrency it was. It should start
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+without TC parameters, but you never know. So if it doesn't, start with
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+--thread-concurrency 8192 and add 2048 to it at a time till you find the highest
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+value it will start successfully at.
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+
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+Then start overclocking the eyeballs off your memory, as 7970s are exquisitely
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+sensitive to memory speed and amazingly overclockable but please make sure it
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+keeps adequately cooled with --auto-fan! Do it while it's running from the GPU
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+menu. Go up by 25 at a time every 30 seconds or so until your GPU crashes. Then
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+reboot and start it 25 lower as a rough start. One example runs stable at 1900
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+memory without overvolting. Overvolting is the only thing that can actually
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+damage your GPU so I wouldn't recommend it at all.
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+
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+Then once you find the maximum memory clock speed, you need to find the sweet
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+spot engine clock speed that matches it. It's a fine line where one more MHz
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+will make the hashrate drop by 20%. It's somewhere in the .57 - 0.6 ratio range.
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+Start your engine clock speed at half your memory clock speed and then increase
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+it by 5 at a time. The hashrate should climb a little each rise in engine speed
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+and then suddenly drop above a certain value. Decrease it by 1 then until you
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+find it climbs dramatically. If your engine clock speed cannot get that high
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+without crashing the GPU, you will have to use a lower memclock.
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+
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+Then, and only then, bother trying to increase intensity further.
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+
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+My final settings were:
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+--gpu-engine 1157 --gpu-memclock 1900 -I 20
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+for a hashrate of 725kH.
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+
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+Note I did not bother setting a thread concurrency. Once you have the magic
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+endpoint, look at what tc was chosen by the bin file generated and then hard
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+code that in next time (eg --thread-concurrency 22336) as slight changes in
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+thread concurrency will happen every time if you don't specify one, and the tc
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+to clock ratios are critical!
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+
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+Your numbers will be your numbers depending on your hardware combination and OS,
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+so don't expect to get exactly the same results!
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+
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+---
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If you wish to donate to the author of scrypt support, Con Kolivas, please send
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your donations to:
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Luke Dashjr