Bitcoin Forum

Hello All.

Im not a "newbie" anymore with mining, but this forum only let me to post here.
Hope some experts are reading as well.

Ok, so the issue, im posting about.

Im using cgminer for scrypt mining (3.7.2)
Im running an ATI HD 7990 card with 2 GPUs.
Its working fine, mining running smooth.

But:

Sometimes im experiencing some strange things.

Set Intensity 12 for both GPUs
and
GPU thread is on 2

so far settings for both GPUs are the same !

Even sometimes one of the GPUs (GPU0) is hashing at lower hashrate than GPU1 and its temperature is a bit higher, despite it is hashing lower.
Temp difference is about 5-6C at 75-80C level.
Im letting them up till MAX 85C, but even if they are hashing lower (set intensity 11 or 10) the temp difference is steady.


My question.
What could be the reason of temp difference and why is GPU0 is hashing lower sometimes ?

Here are my settings:

{
"pools" : [
   {
      "url" : "http://fast-pool.com:3333",
      "user" : "Coin_millionair.worker_DGC",
      "pass" : "************"
   },
   {
      "url" : "http://doge.pool.webxass.de:3333",
      "user" : "Coin_millionair.worker_DGC",
      "pass" : "************"
   },
   {
      "url" : "http://doge.hashfaster.com:3339",
      "user" : "Coin_millionair.worker_DGC",
      "pass" : "************"
   }
],

"intensity" : "12,12",
"vectors" : "1,1",
"worksize" : "256,256",
"kernel" : "scrypt,scrypt",
"lookup-gap" : "0,0",
"thread-concurrency" : "8192,8192",
"shaders" : "2048,2048",
"gpu-engine" : "0-0,0-0",
"gpu-fan" : "0-85,0-85",
"gpu-memclock" : "0,0",
"gpu-memdiff" : "0,0",
"gpu-powertune" : "0,0",
"gpu-vddc" : "0.000,0.000",
"temp-cutoff" : "85,85",
"temp-overheat" : "81,81",
"temp-target" : "78,78",
"auto-fan" : true,
"auto-gpu" : true,
"api-mcast-port" : "4028",
"api-port" : "4028",
"expiry" : "120",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "2",
"hotplug" : "5",
"log" : "5",
"no-pool-disable" : true,
"failover-only" : true,
"queue" : "1",
"scan-time" : "30",
"scrypt" : true,
"temp-hysteresis" : "3",
"shares" : "0",

"kernel-path" : "/usr/local/bin"
}



Should i try with some different settings ?
Expert recommendations are welcome...

Thank You in advance...

Noone is here with experience to advice ???

did you tweak the core clock?
if not, you should. but, careful - don't increase it more than 10%. if it becomes unstable, lower it by half the increase and check again.

My experience with multi-core graphics cards is one always mines slightly slower that the other and they are hardly ever the same temperature. :P  It seems to be just a feature of the way the card is made.  I always upped the core clock on the second GPU to get a few more MH/s out of it and even out the temperatures. ;)

Ooooh, ok. So it is normal ! Great :)
Btw, i think i've figured out the reason:
GPU0 is the main GPU, and hashrate is decreasing and temp is increasing when i am using the computer, such as web browsing or sum light usage only ofcourse.
Probably GPU0 is doing the main tasks, so when im using it, its a bit overloaded, so thats why.
When i leave the puter alone (Close all webbrowsing and ather apps. Only mining) after a few min hashrate for both GPUs getting the same hashrate.
GPU0 temp is still higher with 2-3C, but i can live with that.


Anyways, i have tweaked the coreclock and memclock as well.
Set it to auto, so CGminer is doing that job:
"gpu-engine" : "0-0,0-0",
"gpu-fan" : "0-85,0-85",
"gpu-memclock" : "0,0",


I have set in CCC AMD overdrive enabled.
Coreclock is up to 1100, memclock is up to 1500 when hashing...


Thanks for the answers tough...