Radeon R9 290/290X Litecoin Mining: New Settings and Revised Expectations

Over the past several weeks I've had a flood of comments and emails about R9 290/290X hashing performance when mining Litecoins (or any other scrypt-based cryptocurrency). Initial experience with the cards suggests that the Radeon R9 290 can hit up to 900KHash and the Radeon R9 290X can hit 1000KHash, but the key part of that is "up to". In practice, the cards vary, sometimes wildly.

There are a lot of 290X cards that seem to top out in the 800-850KHash range, and short of adding better cooling I'm not sure how much farther you can push them. R9 290 tends to be more like 750-800KHash on a lot of cards. I think if we could get voltage adjustments working, we might be able to improve on those results for a lot of cards, but we probably won't have that for a few more weeks if not months.

One of the keys to understanding what's required for tuning performance on the new Hawaii R9 290/290X cards is that AMD has built in safety protocols to keep the cards running "safely". A lot of people have tried my original settings and come up with far lower performance than expected. This is why I provided batch files to help you tune and tweak performance.

Scrypt hashing by design is far more memory intensive than SHA256 hashing. The idea was to make it impossible or at least impractical to do scrypt hashing on GPUs, let along FPGAs and ASICs. So far, no one has yet released any FPGA or ASIC hardware for scrypt devices, and I suspect we're probably still at least a year away from such hardware becoming publicly available. (There may be early hardware undergoing "testing" for month in China or elsewhere first, of course.) So when you're looking to fine-tune your GPUs, start with the memory clocks and push those as far as you can while maintaining stability -- and maybe add a few extra cooling fans to help out! If you want to hit extremely high hash rates, you'll want the memory clock at 1600MHz or higher, and most cards won't do that without some sort of additional cooling or other modification.

Once you've found the maximum reliable memory clocks for your GPUs, only then should you start tuning the GPU clock speed. What's interesting is that even though most cards will happily accept GPU engine clocks of 1000MHz or higher, in reality they'll often run at far lower clocks -- this is AMD's safety protocols kicking in. So if you start off at 950MHz core and 1350MHz RAM and a thread concurrency of 32000 (give or take), and you find your hash rates are closer to 600 or 700KHash rather than 800-900KHash, don't despair!

Start with a lower GPU clock of around 800MHz (on R9 290/290X) and then start bumping it up 25MHz after about 10 minutes or more testing at each clock speed. You'll most likely find that 850MHz ends up being the sweet spot, and then you can play with clocks a bit more bumping it up/down in 5MHz increments to see if you can squeeze a bit better performance out of your system. When all of that is done, only then should you bother with tweaking your thread concurrency.

And with that said, here are my revised settings for R9 290/290X graphics cards. I'm going to include cgminer settings for four cards as an example this time, just to illustrate what you would use. I've also included three pools, the first two being multi-coin pools, since that's what I use these days. I'm also going to try toying around with BFGminer to see if I can coax anything better out of it. For the time being, these settings are more or less "stable".

cgminer.conf settings for ~810 KHash R9 290X / ~770 KHash R9 290

{
"pools" : [
{
"url" : "http://stratum01.hashco.ws:8888",
"user" : "trogdorjw73.tester",
"pass" : "tester"
},
{
"url" : "stratum+tcp://middlecoin.com:3333",
"user" : "13saHMFfUAv1crYp3QLbFr9aP1JYnb89oh",
"pass" : "x"
},
{
"url" : "http://coinotron.com:3334",
"user" : "trogdorjw73.tester",
"pass" : "tester"
}
]
,
"intensity" : "20,20,20,20",
"worksize" : "256",
"kernel" : "scrypt",
"lookup-gap" : "2",
"thread-concurrency" : "24272,24272,24272,24272",
"gpu-engine" : "850-850,850-850,850-850,850-850",
"gpu-fan" : "45-85,45-85,45-85,45-85",
"gpu-memclock" : "1475,1475,1475,1475",
"gpu-memdiff" : "0,0,0,0",
"gpu-powertune" : "50,50,50,50",
"gpu-vddc" : "1.100,1.100,1.100,1.100",
"temp-cutoff" : "100,100,100,100",
"temp-overheat" : "95,95,95,95",
"temp-target" : "85,85,85,85",
"api-mcast-port" : "4028",
"api-port" : "4028",
"auto-fan" : true,
"expiry" : "120",
"failover-only" : true,
"gpu-dyninterval" : "7",
"gpu-platform" : "1",
"gpu-threads" : "1",
"hotplug" : "5",
"log" : "5",
"no-pool-disable" : true,
"queue" : "1",
"scan-time" : "60",
"scrypt" : true,
"temp-hysteresis" : "3",
"shares" : "0",
"kernel-path" : "/usr/local/bin"
}

And just in case this isn't clear, with the above settings you would launch cgminer.exe with the following command:

cgminer.exe --auto-fan --config cgminer.conf --failover-only