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Topic: Dual 6990s (Read 9137 times)

newbie
Activity: 32
Merit: 0
June 04, 2011, 08:14:31 PM
#41
I accidentally mined a load of bitcoins when I left the client running on my server for a month last year.
I discovered them a couple of weeks ago - so immediately decided I liked bitcoins and I should use the cash to buy a new rig - i7 with two 6990s fed with a Corsair 1200W.
Can't speak of the power consumption of the individual components, but I can get the wattage the whole box is drawing from the plug.

Whole system running at stock speed originally pulled about 920W. Once I'd sussed that I forced each of the poclbm processes to all use the same CPU core, that dropped to about 850W.
Upping the GPU speed to 850MHz and the memory down to 625Mhz (For some reason even fiddling with config file, I can't get afterburner to allow lower), it now happily runs at 720W.

I'm pretty sure I've still got some 'issues' with the system though. I'm currently using poclbm and that's giving me ~340MHash/s per GPU core. Not good, but not bad - tried poclbm-mod, phoenix and even after playing with config for a bit, still can't get any noticable speed increase. Strange thing is that if I up the GPU cores (giving a little bit more voltage), it doesn't seem to make any real difference in speed and just starts to guzzle the power.
Only thing I can guess is that there's some kind of bottleneck somewhere. Currently it looks like I need to have Crossfire enabled (without it only see 2 GPUs and they don't seem to run as fast). Going to have a play with some resisters to make a dummy plug when I have some time.

#edit - just realized I had some resistors in a drawer over my desk so have it a go - no luck. I just see Cayman core 0 and 1
full member
Activity: 154
Merit: 100
April 11, 2011, 01:01:46 AM
#40
Do you happen to know the power consumption of that card at 746 Mhash/s (mrb: edited)?

Yep:

HD 6990 (@sw1, 880MHz): 746 Mhash/s, 410 W, 1.82 Mhash/s/W
HD 6990 (@sw2, 830MHz, default): 683 Mhash/s, 346 W, 1.97 Mhash/s/W
HD 5970: 569 Mhash/s, 275 W, 2.07 Mhash/s/W
(Measurements taken while running hdminer, with a clamp meter at the three sources of power: slot + two power connectors.)

I would not recommend to mine at 880MHz since it is about 8% less power efficient than at 830MHz. Also, contrary to what is believed, the Mhash/s/W rate of the HD 6990 is not so bad at 830MHz when compared to the good old 5970.

Awesome! Thanks for posting this.
legendary
Activity: 3920
Merit: 2349
Eadem mutata resurgo
April 10, 2011, 09:58:56 PM
#39
Too late. They are racked and mining. Sorry Undecided I will have more time for optimizing the power consumption when/if I get a next batch of cards.

guys, how do I go about reducing the mem clock using ubuntu? As I understand it one could use afterburner under windows but I am not too sure about ubuntu.

Doesn't help on linux, apparently, althought yet to test this myself ... you might find some useful tips here.

https://bitcointalksearch.org/topic/underclock-mem-speed-on-hd-5970-linux-4806

I think you might have your hands full just getting the 6990 up and running on ubuntu with full driver/OpenCL support etc ...
newbie
Activity: 6
Merit: 0
April 10, 2011, 07:02:54 PM
#38
Too late. They are racked and mining. Sorry Undecided I will have more time for optimizing the power consumption when/if I get a next batch of cards.

guys, how do I go about reducing the mem clock using ubuntu? As I understand it one could use afterburner under windows but I am not too sure about ubuntu.
mrb
legendary
Activity: 1512
Merit: 1028
April 10, 2011, 06:08:43 PM
#37
Too late. They are racked and mining. Sorry Undecided I will have more time for optimizing the power consumption when/if I get a next batch of cards.
full member
Activity: 126
Merit: 100
April 10, 2011, 05:32:27 PM
#36
Do you happen to know the power consumption of that card at 746 Mhash/s (mrb: edited)?

Yep:

HD 6990 (@sw1, 880MHz): 746 Mhash/s, 410 W, 1.82 Mhash/s/W
HD 6990 (@sw2, 830MHz, default): 683 Mhash/s, 346 W, 1.97 Mhash/s/W
HD 5970: 569 Mhash/s, 275 W, 2.07 Mhash/s/W
(Measurements taken while running hdminer, with a clamp meter at the three sources of power: slot + two power connectors.)

I would not recommend to mine at 880MHz since it is about 8% less power efficient than at 830MHz. Also, contrary to what is believed, the Mhash/s/W rate of the HD 6990 is not so bad at 830MHz when compared to the good old 5970.

can you try with mem clocks at like 150 for the 6990 and 300 for the 5970 please? Cheesy
mrb
legendary
Activity: 1512
Merit: 1028
April 10, 2011, 05:06:19 PM
#35
Do you happen to know the power consumption of that card at 746 Mhash/s (mrb: edited)?

Yep:

HD 6990 (@sw1, 880MHz): 746 Mhash/s, 410 W, 1.82 Mhash/J
HD 6990 (@sw2, 830MHz, default): 708 Mhash/s, 346 W, 2.05 Mhash/J
HD 5970: 569 Mhash/s, 275 W, 2.07 Mhash/J
(Measurements taken while running hdminer, with a clamp meter at the three sources of power: slot + two power connectors.)

I would not recommend to mine at 880MHz since it is about 8% less power efficient than at 830MHz. Also, contrary to what is believed, the Mhash/J rate of the HD 6990 is not so bad at 830MHz when compared to the good old 5970.
full member
Activity: 126
Merit: 100
April 06, 2011, 10:32:12 PM
#34
The 6990s will arrive tomorrow.

Which ones did you get, and have there been any overclocking comparisons among the various brands?  I imagine they are all reference designs at this point.

they are all mostly reference
hero member
Activity: 726
Merit: 500
April 06, 2011, 10:09:28 PM
#33
The 6990s will arrive tomorrow.

Which ones did you get, and have there been any overclocking comparisons among the various brands?  I imagine they are all reference designs at this point.
full member
Activity: 154
Merit: 100
April 06, 2011, 06:43:36 PM
#32
Okay guys, thanks for all of the feedback. There has been some repast good discussion here. It amazing how members of the community contribute so much.

Well ive decided to go for a rig that consists if 2 x 6990s

My next rig will most probably be a trifire with 1 x 5970 and 2 x 5870 (eta 3 days)

The 6990s will arrive tomorrow.

I can unbox and give my initial results if you like.


Results would certainly be appreciated!
newbie
Activity: 6
Merit: 0
April 06, 2011, 06:36:55 PM
#31
Okay guys, thanks for all of the feedback. There has been some repast good discussion here. It amazing how members of the community contribute so much.

Well ive decided to go for a rig that consists if 2 x 6990s

My next rig will most probably be a trifire with 1 x 5970 and 2 x 5870 (eta 3 days)

The 6990s will arrive tomorrow.

I can unbox and give my initial results if you like.
full member
Activity: 154
Merit: 100
April 06, 2011, 05:36:45 PM
#30
Undervolting memory may only be supported through BIOS mods...

it would be interesting to know about power consumption at lower mem clocks. If you REALLY want to know, I can ask him, provided I give him enough $$. I would need something like 15~20$ I guess. If enough people want this and contribute, I can ask him ho much he wants, perhaps he would do the same for a 5870 and 5870 if he still has those too.

I've checked all of my current BIOS (5850 / 5870) and unfortunately I can't access the VTT registers in any of them.

I do want to know, but I'm patient and not looking to purchase any 6990s in the very near future. I'm sure there will be miners that use them and are willing to provide their info. While it may not be as accurate as W1zzard's, it will be interesting none-the-less.
full member
Activity: 126
Merit: 100
April 06, 2011, 05:18:06 PM
#29
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate

I wasn't suggesting that the results on the chart were inaccurate. He doesn't underclock his memory, which is my primary concern. Also, he probably isn't mining when he takes those readings! Hmm, his method wouldn't account for power supply efficiency either.

If it did, it wouldn't be accurate would it?

Let me clarify. I don't necessarily care how much power the cards consume, other than it's a nice guide. I care about how much power the cards consume when mining bitcoins (to the best of their ability)!

When comparing, you CANNOT take that number unless you are talking theoretically. Else it is VERY innacurate. at 356W, at 80% it takes 445W while at 85% it takes 418W. It depends on too many factors for it to mean anything

Do not forget that if you are solely using you computer for mining, you might as well take into consideration whole system power consumption. 

I never said he should, just that he didn't. This is a good thing. It was merely a comment on some of the things that vary from his chart to actual mining usage!

Of course I take into consideration whole system power consumption. Why would I be concerned about how much power is saved from underclocking the memory if I wasn't looking to save power elsewhere? That said, most of my power consumption comes from the video cards. I am bothered about CPU usage with multiple cards in Windows though.

Again. Those numbers are a great guide, but I'm more concerned about actual mining usage. The main thing I'm looking for is how much power is saved on a 6990 by underclocking the memory, as it seems like it could be significant. His chart does me no good except give a reference point of max consumption. It would also be interesting to know if the card supports undervolting the memory.

Undervolting memory may only be supported through BIOS mods...

it would be interesting to know about power consumption at lower mem clocks. If you REALLY want to know, I can ask him, provided I give him enough $$. I would need something like 15~20$ I guess. If enough people want this and contribute, I can ask him ho much he wants, perhaps he would do the same for a 5870 and 5870 if he still has those too.
full member
Activity: 154
Merit: 100
April 06, 2011, 04:53:28 PM
#28
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate

I wasn't suggesting that the results on the chart were inaccurate. He doesn't underclock his memory, which is my primary concern. Also, he probably isn't mining when he takes those readings! Hmm, his method wouldn't account for power supply efficiency either.

If it did, it wouldn't be accurate would it?

Let me clarify. I don't necessarily care how much power the cards consume, other than it's a nice guide. I care about how much power the cards consume when mining bitcoins (to the best of their ability)!

When comparing, you CANNOT take that number unless you are talking theoretically. Else it is VERY innacurate. at 356W, at 80% it takes 445W while at 85% it takes 418W. It depends on too many factors for it to mean anything

Do not forget that if you are solely using you computer for mining, you might as well take into consideration whole system power consumption. 

I never said he should, just that he didn't. This is a good thing. It was merely a comment on some of the things that vary from his chart to actual mining usage!

Of course I take into consideration whole system power consumption. Why would I be concerned about how much power is saved from underclocking the memory if I wasn't looking to save power elsewhere? That said, most of my power consumption comes from the video cards. I am bothered about CPU usage with multiple cards in Windows though.

Again. Those numbers are a great guide, but I'm more concerned about actual mining usage. The main thing I'm looking for is how much power is saved on a 6990 by underclocking the memory, as it seems like it could be significant. His chart does me no good except give a reference point of max consumption. It would also be interesting to know if the card supports undervolting the memory.
full member
Activity: 126
Merit: 100
April 06, 2011, 03:27:06 PM
#27
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate

I wasn't suggesting that the results on the chart were inaccurate. He doesn't underclock his memory, which is my primary concern. Also, he probably isn't mining when he takes those readings! Hmm, his method wouldn't account for power supply efficiency either.

If it did, it wouldn't be accurate would it?

Let me clarify. I don't necessarily care how much power the cards consume, other than it's a nice guide. I care about how much power the cards consume when mining bitcoins (to the best of their ability)!

When comparing, you CANNOT take that number unless you are talking theoretically. Else it is VERY innacurate. at 356W, at 80% it takes 445W while at 85% it takes 418W. It depends on too many factors for it to mean anything

Do not forget that if you are solely using you computer for mining, you might as well take into consideration whole system power consumption. 
full member
Activity: 154
Merit: 100
April 06, 2011, 03:23:02 PM
#26
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate

I wasn't suggesting that the results on the chart were inaccurate. He doesn't underclock his memory, which is my primary concern. Also, he probably isn't mining when he takes those readings! Hmm, his method wouldn't account for power supply efficiency either.

If it did, it wouldn't be accurate would it?

Let me clarify. I don't necessarily care how much power the cards consume, other than it's a nice guide. I care about how much power the cards consume when mining bitcoins (to the best of their ability)!
full member
Activity: 126
Merit: 100
April 06, 2011, 03:20:39 PM
#25
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate

I wasn't suggesting that the results on the chart were inaccurate. He doesn't underclock his memory, which is my primary concern. Also, he probably isn't mining when he takes those readings! Hmm, his method wouldn't account for power supply efficiency either.

If it did, it wouldn't be accurate would it? No reviewer should EVER take into account PSU efficiency. PSU efficiency is not constant, nor is it the same from PSu to PSU, even if it is the same model

If you have a good PSU, you can say your efficiency is about 80~85% though. to give an idea, at 356W, with 85% eff, it takes 418.8W AC.
full member
Activity: 154
Merit: 100
April 06, 2011, 03:03:17 PM
#24
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate

I wasn't suggesting that the results on the chart were inaccurate. He doesn't underclock his memory, which is my primary concern. Also, he probably isn't mining when he takes those readings! Hmm, his method wouldn't account for power supply efficiency either.
full member
Activity: 126
Merit: 100
April 06, 2011, 02:42:14 PM
#23
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.

The machine they use to take the power from that is a Keithley Integra 2700, a 1600$ machine that measures from the pci-e slot.... W1zzard has been into reviewing since a long time as well.... I believe his results are very accurate
full member
Activity: 154
Merit: 100
April 06, 2011, 02:34:26 PM
#22
http://tpucdn.com/reviews/ASUS/Radeon_HD_6990/images/power_maximum.gif

from http://www.techpowerup.com/reviews/ASUS/Radeon_HD_6990/20.html  Their reviews are the best on the web IMO. One of the reasons I'm an active member over there. These are max figures, meaning the most you could draw from the card (ie: 100% load Furmark etc etc). I do not know if the power consumption is for 830Mhz core, but I believe it is. In your review, they state that the power consumption goes up by 18W for 880 core, so total Power consumption for the 6990 st 880Mhz should be 356W. There is a memory voltage bump, I believe, between the 2 BIOSes however, so keeping the 830 core BIOS but OCing to 880Mhz and downclocking to 150 mem (default idle clock, which is much lower than that of a 5970!!!) should definitively drop the Power consumption. I'm inclined to say that 5970 at 5870 core speed and 300 mem would definitively need more power than a 6990 at 6970 core speed and 150 mem.

True, the 6990s power consumption should be lower, but it would be awesome to know how much lower. The chart gives some figures to work with, but it would be great to have some data from actual miners as well. I have a 5870 that differs 27W from the chart, for several reasons I'm sure. It would be great to see how much the 6990 can benefit from a memory underclock. It certainly seems like there is a lot of potential there.

I'm looking for reasons to justify the 6990 in a hashing machine. For me, it all comes down to value. New tech is fun and exciting, but if there is minimal benefit for massive price increases, there is no point for me to spend the extra money.

As far as resale value, every day I see used 5870s selling for more than I paid for a new one.
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