Overclocking 8800GT via NiBiTor

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Overclocking 8800GT via NiBiTor

Postby nbucko » Tue Apr 27, 2010 8:08 pm

I've finally managed to get multiple GPU's folding headless under Ubuntu. I've got two 8800gt's and I believe that they are running way too slow. The first work unit for each card took about 12-14 hours to complete. I've done some reading and found that most that overclock their cards are getting much better results than that.

I got nvflash and NiBiTor and have been able to get a copy of the BIOS for both cards. In NiBiTor under the Clockrates tab there are four rows that are Extra, 3D, Thrtl and 2D. There are also three columns that are Core, Shader and Memory. I've heard everyone saying that the shaders are what need to be overclocked to get the most out of your GPU. When I read the default BIOS for the cards the only row that has anything in it is the Extra row. 3D, Thrtl and 2D are all filled with 0's.

Do I need to put something into these rows? I've tried putting the same values into these rows as I have in the Extra row but now F@H crashes as soon as I start it up.

I do not have the ability to put these cards into a Windows machine to find out the max values for anything.

Please point me in the right direction...
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Re: Overclocking 8800GT via NiBiTor

Postby uncle fuzzy » Tue Apr 27, 2010 9:45 pm

To fold at full speed you need to force constant 3D clocks. I just use the factory OC (in Windows), so I'll let some one else give specifics on the values you need. I'd say find the stock clocks for the cards and enter those.
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Re: Overclocking 8800GT via NiBiTor

Postby Slash_2CPU » Wed Apr 28, 2010 3:00 am

You need to make sure the "Extra" voltage level(s) are applied as well. If 2D voltage is 1.05V, and 3D is 1.22V, there is no way you will get stable 3D clocks at 2D Volts. Check out the voltage tab, and set Voltage 1 and Voltage 2 to whatever the highest of the 2 of those is already set to.

They may be labeled Extra, 3D, thrtl, and 2D, depending upon your BIOS type. Leave Thrtl at default(if it's even an option), since this is what the card is supposed to step down to if it's overheating.

*Those voltages are listed as examples only. Use what your card has for default "Extra."
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Re: Overclocking 8800GT via NiBiTor

Postby extrasalty » Wed Apr 28, 2010 6:12 am

As far as I know from my 880GT, it doesn't use multiple clocks (2D or3D). I did flash it only after extensive burn-in test to find out the maximum values. I wound up going from 1.05 to 1.1v to get 756 core/1850 shaders.
Based on your post I will recommend AGAINST using NIBITOR.
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Re: Overclocking 8800GT via NiBiTor

Postby nbucko » Wed Apr 28, 2010 8:44 pm

OK, if you don't recommend using nibitor do you know of a utility I can use in Linux or from a dos boot disk (USB drive)?
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Re: Overclocking 8800GT via NiBiTor

Postby extrasalty » Thu Apr 29, 2010 7:16 am

The reason I'm recommending against NIBITOR is not the tool- as I pointed out I flashed my own card with it- it's the circumstances.
First of all, what are your current clocks?
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