Thanks for all the info! I did try to downclock the memory, however when I do it shows in GPUz to still be running at the stock settings (ie I am unable to underclock the memory). Also I am using the twin turbo accellerro cooler and even though I have the fan set to 100 percent it shows it as 30 from gpuz for one core but 100 for the other core. Guessing there is some problemm with reading the fan settings? Because I'm quite sure at 30 percent the temperature would be much higher! Any suggestions on why I am unable to lower my memory clock?
Oh also I should mention in gpuz it shows that the mem clock has been reduced but on the real-time stats page it shows its still running at default speeds. Thanks!
Topic: 6990 Mining Blues - page 2. (Read 1687 times)
^^ +1 Was just about to suggest that you also ramp your fan to ~60-80%
Typically temps that get into 90C+ range will cause the card to throttle; it'll continue mining but hashrate will drop to about half every few seconds. Since your 6990 isn't being used to drive any displays, you should lower the memory clocks of those cores. Like 400MHz memory clocks at the most, as low as is stable pretty much. This will reduce heat/electricity use. I use 5830's mainly, 950MHz GPU clock and 325MHz memory clock. Also, fan is only at 30% in that screenshot? Run your fan at like 75%. It'll be loud, but it'll save your card from fiery death.
Woah I didn't even notice that (hence why I am a newbie LOL!). Downclocked back to 830. Guessing a lack of airflow with the two cards increases heat so much that the core keeps dropping due to high heat?
Dear god! Drop the clocks! Your VRM's are within 8 degrees of frying!! 
Hey Everybody =)
So pretty new to mining, just picked up a 6990 so mining with that in my desktop as a secondary GPU while I have a 7770 driving my display.
However I am having some trouble as the GPU cores keep dropping to 0% load and then back to 100 then back to zero.
I decided to put the bios switch on the card to switch 1, and the problem has disappeared on one gpu core.
On the core in which the problem still occurs, the voltage has increased to 1.175 but drops to 1.0 frequently also dropping the gpu usage to 0% and reducing the clock speed. On the other core which is now working the voltage 1.12. Any ideas what the problem might be? Is there a second bios switch I am missing
I have attached two screen shots for reference, notice how the GPU with 1.12 voltage shows the cores continuously staying at 100%, while the other shows it as 1.175 but is fluctuating in voltage and memory clock while the usage fluctuates from 0-100% as per the spikey chart by GPU usage.
http://s11.postimage.org/oz3enyd0f/pic_1.jpg
http://s11.postimage.org/fsl40o7s3/pic_2.gif
anonymous image hosting
So pretty new to mining, just picked up a 6990 so mining with that in my desktop as a secondary GPU while I have a 7770 driving my display.
However I am having some trouble as the GPU cores keep dropping to 0% load and then back to 100 then back to zero.
I decided to put the bios switch on the card to switch 1, and the problem has disappeared on one gpu core.
On the core in which the problem still occurs, the voltage has increased to 1.175 but drops to 1.0 frequently also dropping the gpu usage to 0% and reducing the clock speed. On the other core which is now working the voltage 1.12. Any ideas what the problem might be? Is there a second bios switch I am missing
I have attached two screen shots for reference, notice how the GPU with 1.12 voltage shows the cores continuously staying at 100%, while the other shows it as 1.175 but is fluctuating in voltage and memory clock while the usage fluctuates from 0-100% as per the spikey chart by GPU usage.
http://s11.postimage.org/oz3enyd0f/pic_1.jpg
http://s11.postimage.org/fsl40o7s3/pic_2.gif
anonymous image hosting
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