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So now that the 7970's have been mining for a couple weeks, what is the rough consensus on efficiency? 

It looks to me that a 7970 gets approximately the same hash rate as a 5970, but with half the GPU's.  Intuitively, this must mean a major increase in efficiency. 

Anyone care to put some numbers with the argument?  I have seen many different figures.....just hoping someone who has followed it more closely can lay out the specifics. 

I already posted a comparison in another thread, but FWIW here it is again:

Single 7970: Roadhog2k5's results (https://bitcointalk.org/index.php?topic=57410.msg683755#msg683755)
System Idle: 270 watts
System Mining: 388 watts
Mining: 925/150mhz,  865mv, 118 watts
550 MH/s (4.66 MH/watt for the card)

Single 5970: My results
System Idle: 138 watts
System Mining: 235 watts
Card Mining: 605/166mhz, 900mv, 97 watts
550 MH/s (5.67 MH/watt for the card)

Of course this is two different systems so the baseline System Idle numbers are different.  Theoretically it shouldn't really matter what the idle baseline numbers are, but it would be nice to see a true back-to-back comparison on the same mining box.

What are your settings on that 5970?  How is the world is a dual GPU card only pulling 97 watts?  That seems insane......

Crazy undervolt.  Kinda interesting, the cores are down at 0.9v

What would one expect a 5970 to draw at stock settings?  I only ask because I have 12 mining away currently. 

Stock voltage:
System Idle: 138 watts
System Mining: 250 watts
Card Mining: 605/166mhz, 950mv, 112 watts
550 MH/s (4.91 MH/watt for the card)

Bear in mind that I cranked the clock down just enough to match the 550 MH/s hash rate of Roadhog2k5's single 7970 just to see what kind of power draw the 5970 would have at the same hash rate.  After some experimentation I found that I could go down to 900mv and still be 24/7 stable.  Just out of curiosity I was playing around this morning and got things working at 885mv which further shaved off a few watts, but I haven't had time to see if it will actually run 24/7 that way.

I can't remember what the power draw is at stock voltage and stock clock, but I can check when I get home tonight.

Edit:  Nevermind this entire post.  I forgot that stock voltage is 1050mv.  For some reason I was thinking it was 950mv... durrr.  I'll measure stock settings after work and report back in when I get some hard numbers.  From what I can remember though, stock voltage with a 825MHz clock (stock is 775MHz I think) my entire rig pulls around 390-400W.  So subtract 138W for system idle and that puts my stock voltage (with OC'd core) 5970 at 252-262W.

all on the same rig
PhenomII @ 1GHz, PSU is the same SF 80+ gold as used before

5970, linux amd64, cat 11.12, sdk2.5
idle @ 0.95V/157/1000, 182W
idle @ 0.95V/157/300, 152W
idle @ 0.95V/157/150, 149W
cgminer @ 1.05V/820/300, 377W, 761Mh/s
cgminer @ 1.05V/600/150, 308W, 542Mh/s
cgminer @ 1.00V/600/150, 291W, 542Mh/s
cgminer @ 0.95V/600/150, 273W, 542Mh/s

7970, linux amd64, cat 11.12, sdk2.6
idle @ 0.85V/300/150, 115W
idle @ 1.175V/300/150, 132W
idle @ 1.175V/1150/1070, 168W
phoenix @ 1.175V/1150/1070, 363W, 676Mh/s
phoenix @ 1.175V/1150/1375, 370W, 676Mh/s
phoenix @ 0.85V/300/200, 154W, 178Mh/s

7970, windows 7, cat 11.12 7970 edition, sdk 2.6
screen off for a bit,102W
idle @ 0.85V/300/150, 114W
idle @ 1.175V/925/150, 142W
idle @ 1.0V/925/150, 128W
phoenix @ 1.0V/925/150, 235W, 535Mh/s
phoenix @ 0.95V/925/150, 222W, 535Mh/s
phoenix @ 0.92V/925/150, 217W, 535Mh/s
phoenix @ 1.175V/1150/150, 328W, 659Mh/s
phoenix @ 1.175V/1150/300, 339W, 666Mh/s
phoenix @ 1.175V/1150/1070, 368W, 674Mh/s

2MB PCI S3 VGA card, linux
idle 101W

so let's run some numbers, using 0.95V as undervolt for 7970...
whole system:
max OC @ stock V: 5970 2.02Mh/J, 7970 2.01
undervolted: 5970 1.99Mh/J, 7970 2.41

assuming system is 100W (well, more or less...)
max OC @ stock V: 5970 2.75Mh/J, 7970 2.89
undervolted: 5970 3.13Mh/J, 7970 4.39

bullshit calc (aka simple load - idle)
max OC @ stock V: 5970 3.38Mh/J, 7970 3.07
undervolted: 5970 4.37Mh/J, 7970 4.95

So, basically it is safe to say the 7970 is solidly more efficient, but not a quantum leap.  Fair? 

Well a quantum leap is the smallest possible change, so... it's a quantum leap ;)
Honestly, for mining I'd prefer 5970s. At least until we get 7990s.
What's somewhat surprising is what a power hog a idle 5970 is, didn't quite expect it to be *that* bad.

also 7970 is still only a single gpu card. You can fit 8 cards in 1 system compared to only 4 5970's (driver limitation), so it has less up-front costs as far as supporting hardware.

Awesome, finally a back-to-back test on the same system... and it looks like the results are pretty close in most of the settings.  The "max OC" part is going to vary from card to card, as is the minimum undervolt, so that will def impact the final numbers as well.  Did you try going any lower than 950mv on the 5970?

My 5970s are all running stable at 920mV and 680Mhz.
Of course, YMMV.

Assuming it is doable to set up and run stable 24/7 for 8x 7970 on a single motherboard...

now what do we get with a 7990?

still wondering

I don't believe 97 watts for both cores on a 5970 mining, even at those low volts, is correct. If you want to get a REAL baseline figure, run the computer with a single regular video card (or integrated), and use -that- for your baseline power. -then- plug in the 5970 and get your idle and load power figures, then we can get the true power figures.

also, looks like I replied to a necro.

Oh wow, it seems like it's been forever since I posted on this.  I no longer have any 5970s, but IIRC the 97 watts was indeed (System Mining - System Idle). That was with a severe undervolt that was kinda/sorta stable.  I think it was 24hr stable, but not 48hr stable. Nonetheless it was a real number though, measured at the wall from a Kill-o-watt meter.

Does it make sense to be mining with 7970, would you loose money or make money ?

i've heard the 7970 is the most efficient mining card..

An undervolted 7970 can reach amazing numbers on very little power.

 I got a bunch of 5970s, 6990s, 7950s and 7970s. Basicly in my experience, 7950 is the most efficient card. And it doesnt pump out as much heat as the rest of the bunch. Too bad there isnt a thread where we could all show results.

well, that's not  best really anyway, since you can pull 757Mh/s at 820/140

I got actual power figures for 5970. I ran a computer equipped with a 450 watt 80PLUS Gold power supply with a single 5870 in it and mined to get a baseline figure. It came to 175 watts with a kill-a-watt. I added a 5970 on top of that and ran both cores at 1v, 760MHz and 152MHz memory and mined on the 5870 plus 5970. Power increased to 425 watts with a kill-a-watt and the 5970 generated 705 MHash/sec.

Radeon 5970 @ 760/152/1v = 705Mhash/sec @ 250 watts = 2.82MHash/joule.

 This was brave :D putting those 2 on a 450w supply

It's not brave, it's smart.  He used a Gold PSU, so he probably had close to 450W available on the 12V rails (probably single rail).  If it was a simple Celeron or Sempron 400W could go to the 2 GPUs and if he downclocked the RAM he probably had enough room to throw a 7770 in there too :P

A cheap 450 PSU will have 240W available on the 12v (maybe 20A), a high end Gold PSU is made for this stuff - no need for overkill.  Quality over quantity.

You are correct. I stopped using cheapo power supplies. 80plus gold or better for me from now on. Entire capacity can be drawn on 12v. Rosewill Capstone 450W. Didn't even get warm. On the other end, I have an Antec TruPower II 550 watt. It's something like 70% efficient, no active PFC, and available 12v power is poor. It shut off when I was furmark testing a Radeon 6970. No other video cards were attached.

well then i'm sad...I have a seasonic 1000w plat. psu...it was getting warm with just a 5850 n 7770...and that's off the pcie rails...now i added a 6990 to it and it's getting even hotter...i woulda at least thought it could handle the 2 first cards without a sweat...hmm maybe i got a bum one...it is new...oh well if it goes out i can rma it...7 year warrenty yay...oh and that's with the fan switch to normal and the 6990 underclocked...and all the mem on cards underclocked as well...unless it's picking up the heat from the 6990...open case..no fan to move the air either...but it still was getting warm with the 2 cards lying on my desktop away from the cards so i dunno...hell my seasonic 860w plat. psu is powering a 7970 oc'd n 5970 oc'd and it's not even warm...course it does a box fan blowing into it...

Just because a power supply gets warm or hot doesn't mean it's a terrible power supply that's going to die in a couple days. It could just be better at pulling away heat from hotspots. Your Seasonics are great. You should not feel like you got ripped off with a trash power supply. They are top of the line. Parts of it are designed to have tolerances to temperatures over 100C.

ok well i guess i'll just see how long it lasts...Had a OCZ psu for my old 775 system and it lasted 6+years and maybe it would have lasted longer if i didn't move it...after i took it out of the case it never worked again and some caps were blown...could have replaced them but didn't feel the need to..plus it would have been a pain cause it was 5 and 1 was in a tight spot...well thanks for the info :)

When asics kick in, you will be able to sell 7970 as modern gaming cards. Can you say the same for 3+ year old card?