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Author Topic: Undervolting a 5870 and a 5770 to achieve better MH/J performance  (Read 14367 times)
jjiimm_64
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January 18, 2012, 04:12:43 PM
 #21

System Mining: 235 watts
Card Mining: 605/166mhz, 900mv, 97 watts
550 MH/s (5.67 MH/watt)

Thats pretty damn impressive.  I mean BFL yet to ship FPGA only get 10MH/W.

I may undervolt my rigs this summer.  Keeping the garage cool with cards puking out 4KW of heat during August is tough.


I am thinking of undervolting now,  my power cables are already warm pulling too many amps thru them.

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January 18, 2012, 04:27:58 PM
 #22

System Mining: 235 watts
Card Mining: 605/166mhz, 900mv, 97 watts
550 MH/s (5.67 MH/watt)

Thats pretty damn impressive.  I mean BFL yet to ship FPGA only get 10MH/W.

I may undervolt my rigs this summer.  Keeping the garage cool with cards puking out 4KW of heat during August is tough.


I am thinking of undervolting now,  my power cables are already warm pulling too many amps thru them.

That is why I installed a 30A 240V circuit and 30A 240V PDU.  Smiley

The cable from the PDU to the L6-30R outlet is very thick.  With all the insulation I can't tell the exact size of the wire bug I have to guess it is 10 gauge or larger.
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January 18, 2012, 04:43:49 PM
 #23

System Mining: 235 watts
Card Mining: 605/166mhz, 900mv, 97 watts
550 MH/s (5.67 MH/watt)

Thats pretty damn impressive.  I mean BFL yet to ship FPGA only get 10MH/W.

I may undervolt my rigs this summer.  Keeping the garage cool with cards puking out 4KW of heat during August is tough.

... yet the whole system only gets a measly 2.34Mh/J, why do I have the sneaking suspicion someones "idle" numbers are off?

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January 18, 2012, 04:51:33 PM
 #24

System Mining: 235 watts
Card Mining: 605/166mhz, 900mv, 97 watts
550 MH/s (5.67 MH/watt)

Thats pretty damn impressive.  I mean BFL yet to ship FPGA only get 10MH/W.

I may undervolt my rigs this summer.  Keeping the garage cool with cards puking out 4KW of heat during August is tough.

... yet the whole system only gets a measly 2.34Mh/J, why do I have the sneaking suspicion someones "idle" numbers are off?


imho,  idle numbers are useless.   measure watts at the wall, divide by Mhash.  eos

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January 18, 2012, 04:51:39 PM
 #25

... yet the whole system only gets a measly 2.34Mh/J, why do I have the sneaking suspicion someones "idle" numbers are off?

Who builds single graphics card rigs?
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January 18, 2012, 05:19:55 PM
 #26

... yet the whole system only gets a measly 2.34Mh/J, why do I have the sneaking suspicion someones "idle" numbers are off?

My idle numbers are fine.  AMD Phenom II 960T with all but 1 core disabled, and underclocked to 2.85GHz. It kind of jumps between 135-140W just sitting there doing nothing.  I can take a video of my Kill-A-Watt if you'd like?

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January 18, 2012, 05:21:43 PM
 #27

Who builds single graphics card rigs?

I do Smiley  I sold all my h/w after we went under $3.00 per coin, but still kept my 5970 for BF3.  I still mine with it when I'm not busy pwning nubs.

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January 18, 2012, 05:23:13 PM
 #28

imho,  idle numbers are useless.   measure watts at the wall, divide by Mhash.  eos

Exactly, idle numbers are only used to establish a baseline.  "Zero out the scale" so to speak. 

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January 18, 2012, 05:32:34 PM
 #29

Who builds single graphics card rigs?

I do Smiley  I sold all my h/w after we went under $3.00 per coin, but still kept my 5970 for BF3.  I still mine with it when I'm not busy pwning nubs.

DAT said, who builds single card rigs.?    not who mines with just a single card.

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January 18, 2012, 06:32:12 PM
 #30

Yeah I guess nobody purposely builds single card rigs.  They're usually the result of just using whatever you have laying around until you make a decision to sink more money into it.  As the saying goes: A fool and his money are soon Bitcoin miner Smiley

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January 18, 2012, 06:34:36 PM
 #31

Yeah I guess nobody purposely builds single card rigs.  They're usually the result of just using whatever you have laying around until you make a decision to sink more money into it.  As the saying goes: A fool and his money are soon Bitcoin miner Smiley

I wasn't "bashing" you MousePotato.  Just pointing out that "low" system efficiency for a 1 GPU rig is silly.  The non-GPU load is ammortized over a single GPU.  Obviously it would be significantly better over 4 to 8 GPUs.
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January 18, 2012, 06:46:52 PM
 #32

I wasn't "bashing" you MousePotato.  Just pointing out that "low" system efficiency for a 1 GPU rig is silly.  The non-GPU load is ammortized over a single GPU.  Obviously it would be significantly better over 4 to 8 GPUs.

No worries, I understood what you were saying Smiley  Roadhog2k5 posted his results for the 7970 in both single-card and triple-card configuration but since I only have a solitary 5970, all I can offer is my single-card perspective for comparison.

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January 18, 2012, 06:49:55 PM
 #33

imho,  idle numbers are useless.   measure watts at the wall, divide by Mhash.  eos
Exactly, idle numbers are only used to establish a baseline.  "Zero out the scale" so to speak. 
But it doesn't actually zero it out, because you don't know the idle power consumption of the card. This means that adding another card will make complete system consume more power than the numbers in this thread indicate. The only thing these numbers can be used for is to decide if a PC with the tested configuration should be mining if it's already on anyway.
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January 18, 2012, 06:59:04 PM
 #34

But it doesn't actually zero it out, because you don't know the idle power consumption of the card. This means that adding another card will make complete system consume more power than the numbers in this thread indicate. The only thing these numbers can be used for is to decide if a PC with the tested configuration should be mining if it's already on anyway.

I thought about that, and I guess the only way to figure out how much power the card draws at idle is to have two identical cards.  Measure system idle with one card installed, then measure system idle with both cards installed.  The difference between the two is how much power each card consumes at idle.  I'm sure there's other factors involved that might affect the numbers, but that's about the simplest way I can think of.  Of course this doesn't apply to the 79XX series since it has the ability to hibernate GPUs that aren't currently active, so the MH/J for a multi-card 79XX setup are going to appear unusually low simply because system idle draw of a single 7970 is the same as that of a quad 7970 setup as I understand it.

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January 18, 2012, 07:23:21 PM
 #35

I thought about that, and I guess the only way to figure out how much power the card draws at idle is to have two identical cards.

You wouldn't need two identical cards if you can boot headless.  Boot and measure idle w/ no cards installed and with one card installed.

Also a logic puzzle would be to figure out the idle wattage of 2 different cards using no other cards and no headless boot (it can be done but involves multiple boots). Smiley



Quote
Of course this doesn't apply to the 79XX series since it has the ability to hibernate GPUs that aren't currently active, so the MH/J for a multi-card 79XX setup are going to appear unusually low simply because system idle draw of a single 7970 is the same as that very close to that of a quad 7970 setup as I understand it.

The hybernating 7970 uses much less idle power but it isn't 0.  I think AMD claim is <3W.  With 3x 7970 one could get the exact idle and hibernating wattage.
jjiimm_64
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January 18, 2012, 09:31:37 PM
 #36

System Mining: 235 watts
Card Mining: 605/166mhz, 900mv, 97 watts
550 MH/s (5.67 MH/watt)

Thats pretty damn impressive.  I mean BFL yet to ship FPGA only get 10MH/W.

I may undervolt my rigs this summer.  Keeping the garage cool with cards puking out 4KW of heat during August is tough.


I am thinking of undervolting now,  my power cables are already warm pulling too many amps thru them.

That is why I installed a 30A 240V circuit and 30A 240V PDU.  Smiley

The cable from the PDU to the L6-30R outlet is very thick.  With all the insulation I can't tell the exact size of the wire bug I have to guess it is 10 gauge or larger.

I ran the following to the mining shed (100+ feet):

12/3 plus ground
10/2 plus ground

at first I used only the black and reds as hots, which meant I had 3 hots, 2 neuts, 2 grounds.  I soon realized it was not enough:

so now
2 hot 10G off a 30amp double pole
3 hot 12G each off a 20 amp
2 neutrual returns (the old grounds)
gounds go straight to earth. (8foot copper)

this is all run from a subpanel that is fed with a huge gauge alum wire from a 100amp breaker.   I can tell you that every hot wire is warm to the touch, including the breakers!!

I am now looking into getting a separate meter Smiley

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Gerald Davis


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January 18, 2012, 10:40:58 PM
 #37

I ran the following to the mining shed (100+ feet):

12/3 plus ground
10/2 plus ground

...

I can tell you that every hot wire is warm to the touch, including the breakers!!

You are running 240V right to reduce amperage?

If you are then the major difference is likely the 100 foot run.  My outlet is ~5 feet from my distribution panel and the PDU has a 20ft power cord.
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January 18, 2012, 11:19:54 PM
 #38

I'm still trying to figure out the answer to the logic puzzle.  Embarrassed

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Gerald Davis


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January 18, 2012, 11:31:40 PM
 #39

I'm still trying to figure out the answer to the logic puzzle.  Embarrassed

Really.

System A = system w/ only card 1
System B = system w/ only card 2
System C = system w/ card 1 & 2

Boot system 3 times in the configurations above and record total wattage. (Wattage A, B, C).
Calculate the difference for
Wattage C - Wattage A
Wattage C - Wattage B

Wattage A = system idle + card1 idle
Wattage B = system idle + card2 idle
Wattage C = system idle + card1 idle + card2 idle

Thus
(Wattage C - Wattage A) = system idle + card1 idle + card2 idle - ( system idle + card1 idle )
(Wattage C - Wattage A) = system idle + card1 idle + card2 idle - system idle - card1 idle
(Wattage C - Wattage A) =  card2 idle


(Wattage B - Wattage A) = system idle + card1 idle + card2 idle - ( system idle + card2 idle )
(Wattage B - Wattage A) = system idle + card1 idle + card2 idle - system idle - card2 idle
(Wattage B - Wattage A) =  card1 idle

An example (and verification)

Unknown actual values
System Idle = 100W
Card 1 Idle = 15W
Card 2 Idle = 20W

Measured Results
Wattage A = 115W
Wattage B = 120W
Wattage C = 135W

Calculated Results
(Wattage C - Wattage A) = 135W - 115W = 20W  (graphics card 2)
(Wattage C - Wattage B) = 135W - 120W = 15W  (graphics card 1)
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January 18, 2012, 11:34:54 PM
 #40

I thought about that, and I guess the only way to figure out how much power the card draws at idle is to have two identical cards.

You wouldn't need two identical cards if you can boot headless.  Boot and measure idle w/ no cards installed and with one card installed.

Also a logic puzzle would be to figure out the idle wattage of 2 different cards using no other cards and no headless boot (it can be done but involves multiple boots). Smiley



Quote
Of course this doesn't apply to the 79XX series since it has the ability to hibernate GPUs that aren't currently active, so the MH/J for a multi-card 79XX setup are going to appear unusually low simply because system idle draw of a single 7970 is the same as that very close to that of a quad 7970 setup as I understand it.

The hybernating 7970 uses much less idle power but it isn't 0.  I think AMD claim is <3W.  With 3x 7970 one could get the exact idle and hibernating wattage.
your 2 unknown card idle wattages are A and B, your system is X
measure: (X + A), (X + B), (X + A + B)
(X + A) + (X + B) - (X + A + B) = X
(X + A + B) - (X + A) = A
(X + A + B) - (X + B) = B

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