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Author Topic: Any wisdom on optimizing 6970's?  (Read 4203 times)
jjshabadoo
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January 21, 2012, 07:34:14 AM
 #1

I'm also setting up a 6 x 6970 watercooled rig and hope to get some good hash out of it. Can you down clock the memory as easily as the 5 series card in something like cgminer?

What kind of overclocks and hash rates can I expect? What kind of power consumption?

thanks.
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January 21, 2012, 07:38:08 AM
 #2

I'm also setting up a 6 x 6970 watercooled rig and hope to get some good hash out of it. Can you down clock the memory as easily as the 5 series card in something like cgminer?

What kind of overclocks and hash rates can I expect? What kind of power consumption?

thanks.
My 6970s ran stable between 965 and 1015 engine clock speed depending on the card. Unfortunately, they had that factory limitation of only downclocking the memory 125 Mhz lower than the engine speed. I tried flashing the BIOS but the last few generations are hardware limited, not software so it had no effect (this is why I put the gpu-memdiff option in cgminer). With +20% powertune and engine speeds 15 below mentioned above (I wanted stability), I was getting 400-430 Mh/s. It has been estimated each card run like that would be 280-290 Watts. I ran 4 of them with a (very good) 1250 Watt PSU and no problems.

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cuz0882
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January 21, 2012, 08:08:27 AM
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I would expect to burn up your power supply. I have 4 and its at 950 watts. Even with a 1500 watt psu it would be bad. You want to use around 50% of of your power supply to be efficient. I would recommend using two. I run mine at 950 mhz so I can use the pc without having crashes. 6970's are just a terrible choice for mining. I wish I never bought mine. I just leave the memory at 1375. There was no change in any temperatures when I lowering them. If you are using a good setup they should stay cool anyway.
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January 21, 2012, 08:36:48 AM
 #4

I tried flashing the BIOS but the last few generations are hardware limited, not software so it had no effect (this is why I put the gpu-memdiff option in cgminer)

Negative.  The 6970 can have the memory clock changed easily with a BIOS flash.  I have 42 more recent cards all flashed with lower memclock and voltage.  There were problems with atiflash sending the correct commands to a certain ATMEL ROM though.  For a few of the cards, I had to pull them apart and temporarily short 2 pins on the ATMEL to disable write protection while the ROM was flashed.  This ATMEL chip was used on a lot of later 6970s.  Maybe you ran into this problem?  ATIFlash fixed this issue in 3.89:

Code:
Fix issue with flashing Atmel AT25F512B ROMs

With my XFX reference 6970s, I get 1580Mhash @ 683 watts on an OCZ ZX 1250W PSU.  (900Mhz/340Mhz @ 1.050).  They've been stable for months.  If this is a dedicated rig and you underclock the memory/undervolt the core, you can run 6 cards.  Definitely don't do this at stock clock/memory/voltage though.  Your PSU will hate you.


Totally unrelated -- thanks for CGMiner!  My mining operation would was so much more cumbersome before it existed.  Now that it's scaled up to 40Ghash, it would be a nightmare without it.  In fact, toying around with these 7970s has made me wonder how I dealt with it before.  I've silently tossed some donations your way here and there, but I said nothing because I wasn't looking for recognition.  Thanks for the good work!

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sveetsnelda
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January 21, 2012, 08:39:48 AM
 #5

6970's are just a terrible choice for mining. I wish I never bought mine.

If you set them up properly, they really aren't.  A 5870 is certainly preferred, but they really aren't *that* far off from each other if you do it right.


I just leave the memory at 1375. There was no change in any temperatures when I lowering them. If you are using a good setup they should stay cool anyway.

I dropped 100 watts from a 4 card rig just with dropping the memory clocks to 340Mhz.  That heat has to go somewhere.

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January 21, 2012, 11:54:01 AM
 #6

Sapphire reference cards. They most definitely need a hardware modification to allow setting memory clock lower. There were some links showing how to do so with some wire and solder and shit and I decided against it <_<

You're most welcome and thanks for donations =)

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jake262144
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January 21, 2012, 12:27:33 PM
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I would expect to burn up your power supply. I have 4 and its at 950 watts. Even with a 1500 watt psu it would be bad. You want to use around 50% of of your power supply to be efficient.
Bullshit.

Yes, you are most efficient at 50% but by no more than 2 or 3% it your PSU is 80+certified.
Any decent 1200-watter will pull 950W at the wall indefinitely.

As to leaving the memory at 1375, God help you. Even with the hardware-limited "core_clk -125MHz" cards you'd easily drop ±20 W per card. Less power, less heat, less PSU load.
sveetsnelda
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January 21, 2012, 08:11:29 PM
 #8

Sapphire reference cards. They most definitely need a hardware modification to allow setting memory clock lower. There were some links showing how to do so with some wire and solder and shit and I decided against it <_<
Yeah, the link you're referring to about modification was to override the ROM write protection.  It's actually not enabled on any of the ROMs I've encountered (including the recent Sapphire reference 6970 boards), but the ATIFlash utility couldn't send the correct commands to unlock the ROM to erase it if it was flashed in a particular way.  For example, I had 6 identical XFX 6970s that I had purchased new & sealed from Newegg.  I was able to flash 5 of them successfully but the 6th appeared write locked (which required disassembly and a 1 wire solder).  To make things even more odd was that I could no longer flash any of the 5 cards after they had been flashed once.  I understand why it does it now, but I was originally baffled.  Now that ATIFlash has been fixed, I can flash any of the cards without disassembly.

Think of it this way -- the only way you wouldn't need a hardware modification to set memory clock lower is if they stripped the variable clock generator off of the board.  If they did this though, none of ATI's power management features would work properly (the cards scale the clock back when the card is idle or under low load).  All of the cards would be sucking down significant power at idle.

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sveetsnelda
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January 21, 2012, 08:16:09 PM
 #9

I would expect to burn up your power supply. I have 4 and its at 950 watts. Even with a 1500 watt psu it would be bad. You want to use around 50% of of your power supply to be efficient.
Bullshit.

Yes, you are most efficient at 50% but by no more than 2 or 3% it your PSU is 80+certified.
Any decent 1200-watter will pull 950W at the wall indefinitely.

As to leaving the memory at 1375, God help you. Even with the hardware-limited "core_clk -125MHz" cards you'd easily drop ±20 W per card. Less power, less heat, less PSU load.

^all of this.  A bit harsh, but correct.

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January 21, 2012, 09:57:24 PM
 #10

Sapphire reference cards. They most definitely need a hardware modification to allow setting memory clock lower. There were some links showing how to do so with some wire and solder and shit and I decided against it <_<
Yeah, the link you're referring to about modification was to override the ROM write protection.  It's actually not enabled on any of the ROMs I've encountered (including the recent Sapphire reference 6970 boards), but the ATIFlash utility couldn't send the correct commands to unlock the ROM to erase it if it was flashed in a particular way.  For example, I had 6 identical XFX 6970s that I had purchased new & sealed from Newegg.  I was able to flash 5 of them successfully but the 6th appeared write locked (which required disassembly and a 1 wire solder).  To make things even more odd was that I could no longer flash any of the 5 cards after they had been flashed once.  I understand why it does it now, but I was originally baffled.  Now that ATIFlash has been fixed, I can flash any of the cards without disassembly.

Think of it this way -- the only way you wouldn't need a hardware modification to set memory clock lower is if they stripped the variable clock generator off of the board.  If they did this though, none of ATI's power management features would work properly (the cards scale the clock back when the card is idle or under low load).  All of the cards would be sucking down significant power at idle.
So.. you're saying a newer version of atiflash is all I need now?

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jake262144
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January 21, 2012, 11:24:49 PM
 #11

...  A bit harsh, but correct.
It's called shock treatment. Just what the doc prescribes to guys with 30 posts under their belt authoritatively stating that a 1500W monster can't pull 950 Watts Smiley
My point wasn't to be harsh and nasty. I needed to stop the disinformation from being spread around.
jjshabadoo
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January 21, 2012, 11:55:22 PM
 #12

Thank you all very much and I had seen some of your posts sveetsnelda which is why I decided to buy these. I got them for a good price and in the end, they do have good resale as solid gaming cards.

I'm thinking I might have to split the cards into two rigs though, 6 cards just sounds like a headache on one mobo. I have an extra msi 890 FXA-GD70 and a seasonic 750 watt. I'll maybe put three cards on that with a nice 360 rad since the cards came with blocks and then put the other three with a 480 rad I have and try to add a 5870 I have that won't let me control it's fan no matter what i do, bios flash, etc. just easier to handle
I have a seasonic 1250 watt for the 4 card rig also.

Or i could just get a 240 rad for the loop and that would give me a 480 and 240 for the 6 cards which should be fine.

I have the sli fittings for parallel, etc.

will all 6 cards work on an ASUS P8P67 WS motherboard with the right extenders?

So assuming I flash these and get the memclock's down, will this rig work?

ASUS P8P67 WS
6 ATI 6970's with swiftech komodo full waterblocks.
koolance 480 rad with high speed fans (sycthe ultra kaze 3000 rpm)
swiftech mcp 655 pump
swiftech resevoir
240 koolance rad to match i guess, 20 fpi fin density at least(scythe ultra kaze 300 rpm)
seasonic x-1250 gold
i3 2100 cpu, undervolted as much as I can get it
2Gb ram
pci extenders so I can use all the slots on the board.
16GB flash drive running linuxcoin and cgminer.
sveetsnelda
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January 22, 2012, 07:10:39 AM
 #13

So.. you're saying a newer version of atiflash is all I need now?

I believe so.  Took care of it for me.

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January 22, 2012, 08:42:05 AM
 #14

So.. you're saying a newer version of atiflash is all I need now?

I believe so.  Took care of it for me.
Thanks... whenever my freaking motherboard is replaced I'll see about it Smiley

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cuz0882
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January 22, 2012, 11:44:33 AM
 #15

I have sapphire referenced 6970's, there should be no reason to solder or use atiflash. Lower the memory clock is simple but no very important. It won't be a noticeable heat difference. May as well lower it if the pc is only used for mining though. I was adding a new 5970 to a pc that already had 2 in it. And I could not get the voltage or clock speeds to change. I tried several cards and the newly added card would always refuse to change. I finally fixed it by removing all the cards, and running just the card that was giving me problems. It then overclocked fine, and when I put the other cards back in there all set to the correct clocks.
I've also found it very useful to use afterburner for overclocking and running the fans. A lot of people claim to have trouble with it, but if you do it right it works perfectly.
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January 22, 2012, 08:47:45 PM
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there should be no reason to solder or use atiflash
This is only if you're using Windows.  The ATI driver in Linux will not let you lower the memclock further than 125Mhz below core clock.

Lower the memory clock is simple but no very important.
Very wrong.  Lowering memory clock will drop almost 25 watts (AC) per card and won't affect performance.

It won't be a noticeable heat difference.
Yes there will.  25 watts of electricity = 25 watts of heat.  The energy has to come from somewhere.

I've also found it very useful to use afterburner for overclocking and running the fans. A lot of people claim to have trouble with it, but if you do it right it works perfectly.
Afterburner is Windows only.

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jake262144
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January 22, 2012, 09:07:15 PM
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I'll just do some math for our uninformed cuz0882:

OP is setting up a 6 GPU rig.
6 * 25W is 150W less of energy and heat. Still think it's not noticeable?

6970 are very hot GPUs. The 69xx family of cards are flawed products, having been meant to be manufactured at 32nm instead of 40.
Mind you, that it's supposed to be a water-cooled machine.
Removing such levels of heat requires a huge and expensive radiator complemented by a full battery of push-pull high-static-pressure fans and a very strong pump. I'm not sure even a 4*120 radiator will do the job with ease.
Since it's not going to be a walk in the park by any stretch of imagination, it is therefore crucial to minimize the heat footprint before the heat is transported away and dissipated.

Friendly suggestion: when posting on subjects you know little about it would be more appropriate for you to end your posts with a ? instead of a .
jjshabadoo
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January 27, 2012, 03:24:59 PM
 #18

This new atiflash will work for linux, correct? It's one of those dos bios flash programs I assume. I usually have a hard time figuring out how to make it work, but I'll get it eventually.

I just want to be able to lower the memclocks and crank up the OC at stock voltage with cgminer like I do with my 5 series cards.

I'm building this rig for my dad and need it to be pretty stable so I don't have to go over there and work on it all the time.

Hell I can't see any stability issues with water cooling unless I go for a crazy overclock and I'm not going to do that. I jusy want some power savings with the lowered memclock.
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January 29, 2012, 03:08:19 AM
 #19

I can reduce my 6970's mem to 300mhz (or lower) just fine with clocktweak- does this mean I have an unusual card?  Never did any BIOS mods or anything of the sort, just software OCing.

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January 29, 2012, 03:56:22 AM
 #20

I can reduce my 6970's mem to 300mhz (or lower) just fine with clocktweak- does this mean I have an unusual card?  Never did any BIOS mods or anything of the sort, just software OCing.
There is a reason cgminer reports back the CURRENT settings after you change it: It's because the driver will often accept a value you give it, but the hardware will NOT. So you may set it to 300 and it will merrily ignore you and set it back to the default. Try setting it to only 125 lower than the gpu engine speed and if it suddenly starts running cooler than when you "set" it to 300, that is what's happened.

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