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Question about overclocking two 5870's in CF

Reality

Reality

[H]ard|Gawd
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I was able to get both my 5870 2GB cards to run at 1Ghz on each GPU, at 1.2v with MSI afterburner, but while loading each GPU at 100% (With GUIMiner), the MSI Bargraph starts flickering

Is this a heat issue, overvolting issue, or not enough voltage issue?
 
What do you mean by flickering? Do you mean that the image on your monitor out is flashing rapidly or that the graph indicating the amount of load on one or more GPU(s) is swinging wildly? If its the first then you definitely have a stability issue which could be caused by voltage, temperature, the absolute limits of the chip(s) (because each GPU has different overclocking potential), a ram/gpu speed ratio stability issue, or some other miscellaneous but rare issue. Try backing off by about 50Mhz and then slowly working your way up till the first sign of flickering and see if upping the voltage will cure it.
 
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MSI After Burner has a "Sidebar" that you can detach from the main window, that shows bar graphs for GPU Usage, Clock, Voltage, Temps, Fan Speed, etc.

The entire side bar that includes all of these graphs flickers, randomly when pushing the GPU's to 100% @ 1Ghz. To put it another way, it'd be like a game screen flickering if I were playing a game. But this is just a small window that contains constantly updating graphs pertaining to GPU usage, etc. like stated above

Picture:
unledbm.png


The entire window will flicker when loading the GPU to 100% @ 1Ghz
 
If that is the only thing you displayed other than a static background for a desktop, then yeah I think you reached the limits of your GPU(s) if not for the chips themselves then its certainly voltage or temperature related. If you are pushing 1Ghz I hope you have those reference fans at 100% and you memory down clocked to 335 or so. The extra gig of ram adds a bit more heat and the ram generally adds a lot more heat if left at or near stock speeds when the GPU is under load. While I could certainly push my non-reference 5870 to 1015 on stock voltage (because I am limited to stock voltage without a bios flash) I left it at no more than 990 due to thermal issues. In regards to the memory, when I down clocked to just over 1/3 the GPU frequency temps drops about 4 degrees under load.
 
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