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Author Topic: Got me a Kill-a-watt and some 7970's.....  (Read 4380 times)
sveetsnelda
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March 30, 2012, 03:40:19 AM
 #41

My first 7970 came with a number of issues while booting. I had it RMA'd, the new card that just arrived reaches 750 MH/s (1225MHz core, 1375 ram, 1.07 V, 168A) with sensor readings (HWiNFO64) indicate I am pulling 193 watts (Core + RAM).  My first card would already be over 220 watts at these settings, seems either software improved or hardware improved, I used the same drivers from the end of Feb, so probably hardware changed?

This is probably just from leakage.  Each of the cards are going to have a GPU that is "binned" differently.  I've found on my rigs that as soon as I let the temps go much further than 68C, power consumption starts climbing pretty heavily (additional leakage from heat).  If I let the cards in one of my 4 card rigs run at 74-75C, power consumption goes up by almost 100W at the wall.  My 6970s/6870s/5870s/5970s don't do this until they get very hot (80C or above).

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jjiimm_64
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March 30, 2012, 03:40:28 AM
 #42



What... That would mean each 7970 would be getting 825mh... I think you meant 5...

Your absolutely correct...  ooopps  sorry bout that.

My thoughts started with the PSU.  I have a 1250 seasonic pushing 4 of the cards, and then I seen the Mh number and thought he didn't have the updated code.


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ragingazn628
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March 30, 2012, 08:56:15 AM
 #43



What... That would mean each 7970 would be getting 825mh... I think you meant 5...

Your absolutely correct...  ooopps  sorry bout that.

My thoughts started with the PSU.  I have a 1250 seasonic pushing 4 of the cards, and then I seen the Mh number and thought he didn't have the updated code.



You mean 5.

I also have mine undervolted to run much cooler.
jjiimm_64
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March 30, 2012, 12:30:09 PM
 #44



What... That would mean each 7970 would be getting 825mh... I think you meant 5...

Your absolutely correct...  ooopps  sorry bout that.

My thoughts started with the PSU.  I have a 1250 seasonic pushing 4 of the cards, and then I seen the Mh number and thought he didn't have the updated code.



You mean 5.

I also have mine undervolted to run much cooler.


no i meant 4.   the rig has 5 cards, but the seasonic is only on 4 of them. I have another psu powering the 5th card of this mobo and a 5th card on another

10 7970's   2 seasonic 1250  1 seasonic 650


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March 30, 2012, 12:33:50 PM
 #45

My first 7970 came with a number of issues while booting. I had it RMA'd, the new card that just arrived reaches 750 MH/s (1225MHz core, 1375 ram, 1.07 V, 168A) with sensor readings (HWiNFO64) indicate I am pulling 193 watts (Core + RAM).  My first card would already be over 220 watts at these settings, seems either software improved or hardware improved, I used the same drivers from the end of Feb, so probably hardware changed?

This is probably just from leakage.  Each of the cards are going to have a GPU that is "binned" differently.  I've found on my rigs that as soon as I let the temps go much further than 68C, power consumption starts climbing pretty heavily (additional leakage from heat).  If I let the cards in one of my 4 card rigs run at 74-75C, power consumption goes up by almost 100W at the wall.  My 6970s/6870s/5870s/5970s don't do this until they get very hot (80C or above).
This is interesting to note. So as processes get smaller and smaller, power usage will fluctuate more and more widely based on temperature. All the more reason to have good cooling.

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March 30, 2012, 04:47:39 PM
 #46

My first 7970 came with a number of issues while booting. I had it RMA'd, the new card that just arrived reaches 750 MH/s (1225MHz core, 1375 ram, 1.07 V, 168A) with sensor readings (HWiNFO64) indicate I am pulling 193 watts (Core + RAM).  My first card would already be over 220 watts at these settings, seems either software improved or hardware improved, I used the same drivers from the end of Feb, so probably hardware changed?

This is probably just from leakage.  Each of the cards are going to have a GPU that is "binned" differently.  I've found on my rigs that as soon as I let the temps go much further than 68C, power consumption starts climbing pretty heavily (additional leakage from heat).  If I let the cards in one of my 4 card rigs run at 74-75C, power consumption goes up by almost 100W at the wall.  My 6970s/6870s/5870s/5970s don't do this until they get very hot (80C or above).
This is interesting to note. So as processes get smaller and smaller, power usage will fluctuate more and more widely based on temperature. All the more reason to have good cooling.

Yep. Water FTW. About a 40 watt saving per card by going to water for my 7970's.

https://bitcointalk.org/index.php?topic=57410.msg683755#msg683755
sveetsnelda
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March 30, 2012, 06:46:02 PM
 #47

This is interesting to note. So as processes get smaller and smaller, power usage will fluctuate more and more widely based on temperature. All the more reason to have good cooling.
It definitely seems that this is the case.  Even more interesting is the effect this causes when using fans.  If I let the fans go too far beyond the GPU's sweet spot, I actually have to use a similar or higher fan speed to keep the GPU *hotter* (because of the additional wattage).

You certainly hit a "point of no return" though where it costs more energy to spin the fans faster vs the energy you'd save from keeping the chip (and VRMs?) cooler.


Yep. Water FTW. About a 40 watt saving per card by going to water for my 7970's.

https://bitcointalk.org/index.php?topic=57410.msg683755#msg683755
The power savings are substantial, but it's certainly not 40 watts per card (unless you were running the cards very hot on air in the first place).  My water cooled 7970 machine saves about 27 watts (DC) per card (at 36-37c).  Keep in mind that some of the apparent power savings is simply from not having fans on the cards though.  Some of this power to remove the heat gets consumed by the pump and radiator fans.

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Roadhog2k5
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March 30, 2012, 06:58:16 PM
 #48

The power savings is substantial, but it's certainly not 40 watts per card (unless you were running the cards very hot on air in the first place).  My water cooled 7970 machine saves about 27 watts (DC) per card (at 36-37c).  Keep in mind that some of the apparent power savings is simply from not having fans on the cards though.  Some of this power to remove the heat gets consumed by the pump and radiator fans.

They were running about 85c on air. So pretty warm. Went to about 40c on water. The fans do count as power savings in my case too. I already had the cpu watercooled and just add my gpu's to the same loop. No extra pumps, fans or anything.
sveetsnelda
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March 30, 2012, 07:11:11 PM
 #49

They were running about 85c on air. So pretty warm. Went to about 40c on water. The fans do count as power savings in my case too. I already had the cpu watercooled and just add my gpu's to the same loop. No extra pumps, fans or anything.
Ah.  Yeah.  That's pretty hot.  Smiley  Dropping 40-50C will certainly save a good chunk of power.  Cheesy

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