Specs: XFX RX 480 RS 4GB, Hynix Memory, Windows 10 Pro, crimson 16.11.5, Claymore's miner
Long story short: I patched the card with 1375Mhz memory timings, and while now it hashes much faster at default frequency, I can't overclock the memory any further without loosing all the performance benefit that came from BIOS flash.
With stock BIOS it gives 22 MH/s @ 1750Mhz/800mv. The CPU clock doesn't seem to affect anything, so I downclocked it to 1050/900. Next I'm overclocking the memory. After 1751Mhz the hash rate drops to about 18-19 and with raising the frequency I achieved the same freaking 22MH/s at 1960MHz/1100mv. This is the wall for this card.
Patching the BIOS with 1500 timings gave me a boost to 23.1 MH/s @ 1750Mhz or 24.5 MH/s @ 1925Mhz/1100mv.
Then I patched the 1425 timings. The result was 25.2 MH/s @ 1750Mhz.
Next, 1375 timings. 25.8 MH/s @ 1750Mhz, which is already not bad compared to stock BIOS.
But a weird thing started happening when I tried to overclock. No matter how little I change the memory clock, it seems to only harm the performance! Any change at all, and it's down to 18-22MH/s. And it stays there until I revert to 1750Mhz and reboot.
One time I changed the clock to something extreme like 1950Mhz/1100mv and it hashed at 27.2 for a some time until I decided to try something else, which ended in a crash. The settings got reset and I can't reproduce 27.2 anymore. Now it's back to very stable 25.8 MH/s @ 1750, but anything higher than that, and the perormance dies.
Unfortunately, once I've seen 27.2, I can't be satisfied with 25.8.
What is going on? How can I reliably overclock the memory after reducing timings?
Long story short: I patched the card with 1375Mhz memory timings, and while now it hashes much faster at default frequency, I can't overclock the memory any further without loosing all the performance benefit that came from BIOS flash.
With stock BIOS it gives 22 MH/s @ 1750Mhz/800mv. The CPU clock doesn't seem to affect anything, so I downclocked it to 1050/900. Next I'm overclocking the memory. After 1751Mhz the hash rate drops to about 18-19 and with raising the frequency I achieved the same freaking 22MH/s at 1960MHz/1100mv. This is the wall for this card.
Patching the BIOS with 1500 timings gave me a boost to 23.1 MH/s @ 1750Mhz or 24.5 MH/s @ 1925Mhz/1100mv.
Then I patched the 1425 timings. The result was 25.2 MH/s @ 1750Mhz.
Next, 1375 timings. 25.8 MH/s @ 1750Mhz, which is already not bad compared to stock BIOS.
But a weird thing started happening when I tried to overclock. No matter how little I change the memory clock, it seems to only harm the performance! Any change at all, and it's down to 18-22MH/s. And it stays there until I revert to 1750Mhz and reboot.
One time I changed the clock to something extreme like 1950Mhz/1100mv and it hashed at 27.2 for a some time until I decided to try something else, which ended in a crash. The settings got reset and I can't reproduce 27.2 anymore. Now it's back to very stable 25.8 MH/s @ 1750, but anything higher than that, and the perormance dies.
Unfortunately, once I've seen 27.2, I can't be satisfied with 25.8.
What is going on? How can I reliably overclock the memory after reducing timings?