All Tahiti based cards are GCN 1.0 and when the dag changes they slow down by about 0.10MH/s every 5 days.
Currently all my cards hash between 16.5-18.1MH/s or so.
Only way to make them faster is to overvolt and overclock however they become very very inefficient.
However the trick is to undervolt them to the lowest possible voltage, underclock to a stable clock and dual mine SIA while consuming the EXACT SAME power as before.
For example,
ASUS 280X was hashing at 18.1MH/s consuming EXACTLY 190Watts.
I lowered the VDDC to 975 and lowered the clock to 950MH/s. Left the memoryclock the same.
Now it hashes at 16.50MH/s with 247MH/s SIA using EXACTLY 190Watts as before. If you sell the SIA daily and convert back to ETH, you would get an equivalent speed of 19.7MH/s.
My 280X was already undervolted to 1.05V from 1.20V from stock so my gain is only around 9% however if you run yours on the original voltage you should get gains of 20% more using the same power as before.
Your VDDC can't be lower than your #5 VDDC, so the lowest I could do was 950V for mine. I had to set it to 975V because 950V was unstable and the clock has to be lowered to 900/950MHz for it to be stable. Don't do any lower because your ETH speed will be very slow and don't go any higher because it won't run at these low voltages.
My Gigabyte 7970 is running at 900/1500 @ VDDC 950 (lowest possible because of #5 VDDC).
Stock was 17.9MH/s doing ETH only. Now its hashing at 15.25MH/s and 381MH/s which works out to 20.5MH/s when you convert it back. You can use http://www.whattomine.com/merged_coins/2-eth-sc as a guide to help you.
You need to manually set DCRI intensity until your card consumes exactly the same amount of electricity as before. The optimal value will be anywhere between 30-60. My ASUS 280x uses 30 and my Giga 7970 had to use 50. Verify with a Kill-a-Watt or compare your cards temperatures before and after.
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Currently all my cards hash between 16.5-18.1MH/s or so.
Only way to make them faster is to overvolt and overclock however they become very very inefficient.
However the trick is to undervolt them to the lowest possible voltage, underclock to a stable clock and dual mine SIA while consuming the EXACT SAME power as before.
For example,
ASUS 280X was hashing at 18.1MH/s consuming EXACTLY 190Watts.
I lowered the VDDC to 975 and lowered the clock to 950MH/s. Left the memoryclock the same.
Now it hashes at 16.50MH/s with 247MH/s SIA using EXACTLY 190Watts as before. If you sell the SIA daily and convert back to ETH, you would get an equivalent speed of 19.7MH/s.
My 280X was already undervolted to 1.05V from 1.20V from stock so my gain is only around 9% however if you run yours on the original voltage you should get gains of 20% more using the same power as before.
Your VDDC can't be lower than your #5 VDDC, so the lowest I could do was 950V for mine. I had to set it to 975V because 950V was unstable and the clock has to be lowered to 900/950MHz for it to be stable. Don't do any lower because your ETH speed will be very slow and don't go any higher because it won't run at these low voltages.
My Gigabyte 7970 is running at 900/1500 @ VDDC 950 (lowest possible because of #5 VDDC).
Stock was 17.9MH/s doing ETH only. Now its hashing at 15.25MH/s and 381MH/s which works out to 20.5MH/s when you convert it back. You can use http://www.whattomine.com/merged_coins/2-eth-sc as a guide to help you.
You need to manually set DCRI intensity until your card consumes exactly the same amount of electricity as before. The optimal value will be anywhere between 30-60. My ASUS 280x uses 30 and my Giga 7970 had to use 50. Verify with a Kill-a-Watt or compare your cards temperatures before and after.
