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Author Topic: 7970 GPU/MEM Combinations  (Read 4005 times)
bitlane
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June 14, 2012, 07:48:11 AM
 #1

Well, it's all about trial and error....and each time, I either get closer to that magical combination, or further away.

I am now trying 990/180 on my 7970s (Win7 x64, CGMiner 2.4.2). Please share your results.


@ 990 Mhz GPU, 180 Mhz Memory, 1030 mV
-----------------------------------
AthlonII 215 DC (60W), MSI 790FX-GD70, 4GB DDR3, SSD HDD, 5x 7970 Reference = 860W Total System Power (at the plug), 2895 MH/s (#3 in pic)

Xeon e5506 QC (80W), Gigabyte X58A-UD3R, 4GB DDR3, SATA HDD, 5x 7970 Reference = 885W Total System Power (at the plug) 2910 MH/s (#1&2 in pic)



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June 14, 2012, 11:51:54 AM
 #2

If you're going to use stock core voltage (1.17v looks pretty stock to me...), crank up the core speed to increase mh/j slightly and massively increase net throughput. If you're set on those core speeds though, start reducing voltages. Using an excessive amount of voltage for any core speed is just a big waste of electricity and money.

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June 14, 2012, 12:08:57 PM
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If you're going to use stock core voltage (1.17v looks pretty stock to me...), crank up the core speed to increase mh/j slightly and massively increase net throughput. If you're set on those core speeds though, start reducing voltages. Using an excessive amount of voltage for any core speed is just a big waste of electricity and money.

@ 990 Mhz GPU, 180 Mhz Memory, 1030 mV

cgminer does not report proper voltage.

I am still running mine at:  930/800/.937v    5 cards.  835watts at the wall:   2750Mh    do the math

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June 14, 2012, 08:16:24 PM
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so cgminer will set memory to 180mhz now? I think I'm still on lower drivers and have to do 150 mhz difference
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June 14, 2012, 08:33:26 PM
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so cgminer will set memory to 180mhz now? I think I'm still on lower drivers and have to do 150 mhz difference

No, cgminer will only do the 150. I think bitlane is doing the mem with AB

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bitlane
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June 14, 2012, 09:26:41 PM
 #6

Correct. I am using AfterBurner for Memory and Voltage Control, then setting the final GPU clock when launching CGMiner from my bat file.

With this, I can adjust the GPU clocks to anything I want without disrupting the memory clock and having the values revert back to 150Mhz Mem-Diff as well. The memory stays at what I initially set it using AB, even though I change GPU clocks in CGMiner on the fly.

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June 14, 2012, 10:46:57 PM
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I can't get cgminer to change the memory.. Are you in windows?
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June 15, 2012, 01:25:44 AM
 #8

Besides tweaking RAM frequency, GPU frequency, and GPU voltage, has anyone ever dropped the RAM voltage below 1.6 V on a 7970 (I would imagine it would at least take a handful or more of watts away Huh)? I know HIS has an app (HIS iTurbo), by same developers as TRIXX, which allows RAM voltage to be altered, but never heard of anyone doing it for mining bitcoins.

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June 15, 2012, 02:42:53 AM
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all the reading i have done says that messing the with ram voltage is not worth the trouble.

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June 15, 2012, 02:58:57 AM
 #10

I gave it a shot to see what happens, since I run two 7970s massively overclocked on water. The HIS app can lower the voltage down to 1.520 volts. My Kill A Watt says my wattage at the wall is 688, when I undervolted the RAM it reached between 677-680. There does not seem to be any issues that I can perceive: Both GPUs 1275 MHz, RAM  1125 MHz, VDDC 1.187 V (1.088 V in GPU-Z), MVDDC 1.520 V. Each Outputs 760 MH/s, combined ~1520 MH/s. (Electricity is not an issue, so I can overclock by a lot, forgot to mention I also have a 6850 running in the system, not overclocked or mining, but used as primary display).

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June 15, 2012, 04:09:35 AM
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yah,  i used to tell myself i would use a 'card' as display...  it ended up mining too....   

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June 15, 2012, 04:37:51 AM
 #12

Although, one thing is for certain, lowering my two 7970's RAM voltage for the past hour and half shaved off about 11 watts from my system. There does not appear to be any issues, at least so far. In theory, the energy saved would probably be more pronounced if say a system had 8 gpus, with all things being constant, it could reduce power consumption by ~45 watts.


I am tempted to use my 6850, but doing so would significantly exceed my power supply's wattage, and its pretty cheap one too.

Edit: Cannot find the data sheets online for 7970 RAM chips "H5GQ2H24MFR"; though Google shows a pdf listing a chip of equal density running at 1.35 volts (instead of 1.6 V), yet lower in bandwidth. Wonder if 7970's RAM can be used close to such detracted specifications (just curiosity).

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June 15, 2012, 07:58:14 AM
 #13

Although, one thing is for certain, lowering my two 7970's RAM voltage for the past hour and half shaved off about 11 watts from my system. There does not appear to be any issues, at least so far. In theory, the energy saved would probably be more pronounced if say a system had 8 gpus, with all things being constant, it could reduce power consumption by ~45 watts.


I am tempted to use my 6850, but doing so would significantly exceed my power supply's wattage, and its pretty cheap one too.

Edit: Cannot find the data sheets online for 7970 RAM chips "H5GQ2H24MFR"; though Google shows a pdf listing a chip of equal density running at 1.35 volts (instead of 1.6 V), yet lower in bandwidth. Wonder if 7970's RAM can be used close to such detracted specifications (just curiosity).

Running volts lower than recommended won't kill it. Worst case, you'll get artifacts/miner errors/crashes. I say keep going lower and lower until it crashes, and increase it back up til it crashes no more. Save power Smiley

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June 15, 2012, 06:52:45 PM
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cgminer will not allow me to change any voltage or memory clocks.... Is there a way around this?
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June 15, 2012, 07:27:31 PM
 #15

Although, one thing is for certain, lowering my two 7970's RAM voltage for the past hour and half shaved off about 11 watts from my system. There does not appear to be any issues, at least so far. In theory, the energy saved would probably be more pronounced if say a system had 8 gpus, with all things being constant, it could reduce power consumption by ~45 watts.


I am tempted to use my 6850, but doing so would significantly exceed my power supply's wattage, and its pretty cheap one too.

Edit: Cannot find the data sheets online for 7970 RAM chips "H5GQ2H24MFR"; though Google shows a pdf listing a chip of equal density running at 1.35 volts (instead of 1.6 V), yet lower in bandwidth. Wonder if 7970's RAM can be used close to such detracted specifications (just curiosity).

Running volts lower than recommended won't kill it. Worst case, you'll get artifacts/miner errors/crashes. I say keep going lower and lower until it crashes, and increase it back up til it crashes no more. Save power Smiley

I am trying to lower the memory voltage even further, but it appears the tools out there do not go below 1.520 volts. Is there any way to work around this, that is manipulating a config, ini, driver files, or even the registry (HIS iTurbo limits it to 1.520, how does AB compare?)? If it is possible I would like to try lowering the RAM voltage to or below 1.45 V, I wonder if this would drop close to between 15 to 20 watts per 7970 (of course the RAM frequency would also be lowered).

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June 16, 2012, 01:43:46 AM
 #16

Someone said they were able to achieve 1.1 memory volts. Try searching the forums for who.

bitlane
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June 16, 2012, 02:29:40 AM
 #17

cgminer will not allow me to change any voltage or memory clocks.... Is there a way around this?

Afterburner...just like the rest (some ? most ?) of us Wink

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June 16, 2012, 01:01:53 PM
 #18

Trixx seems to fuck shit up for me... doesnt work well with my sapphire card.
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