Bitcoin Forum

I currently have (6) 6xxx series cards in my farm running quite well and considering neither of the 2 models I own are worth jack shit for resale, I figure I would simply run them into the ground and mine them till they die.
They all run extremely stable and cool (under 69c with 50% fan speeds on average or less), so heat is not an issue. I would just like to 'Free Up' a few extra watts from each wall socket that they are plugged into for further expansion.

I have:
- 2x Reference 1GB HD 6870's (limited to 100Mhz mem/gpu clock spread)....currently running 975Mhz GPU/875Mhz MEM on stock Voltage using CGMiner/Win7x64.
- 2x Asus DCUII 1GB HD 6950's  (limited to 125Mhz mem/gpu clock spread)...currently running 900Mhz GPU/775Mhz MEM on stock voltage using CGMiner/Win7x64.
- 2x XFX ZNFC 1GB HD 6950's  (limited to 125Mhz mem/gpu clock spread)....currently running 900Mhz GPU/775Mhz MEM on stock voltage using CGMiner/Win7x64.

(None of the 6950's support Shader unlocking unfortunately)

What I am wondering is...
What kind of power savings could I potentially gain by flashing the above 6 card's BIOS's, underclocking the memory to 300Mhz from their current values ?
....an average 'guess' is fine. I am not expecting dead-nuts numbers.

Anyone care to make an estimate PER CARD ?

Thanks in advance,
bitlane.

18-25watts per card would be my educated guess.

I was hoping to hear around 20W/card.....so if that's correct, that would definitely suffice.

Do you think there is much improvement in power savings going further under the 300Mhz MEM mark ?
...say, the difference between 300Mhz and 180Mhz-ish ? could THAT potentially gain a few extra watts as well ?

You will start getting less MHash if you go below 300. I found that 400 was the best for me.

Is that just for the 6xxx Cards ?
I actually increase MH/s on my 5xxx cards going under 300Mhz MEM, depending on the overclock.
I run my 5830's all @ 975/175 on stock voltage and get 5-8MH/s MORE than if running @ 300Mhz Mem.

Each card is different. Plus I am using 12.1 drivers 2.1SDK and Diablominer from Jan2012. I am sure we are not running the same setup that's why it can be different for each application. On my 6970's I got best results on 12.1 SDK2.6 Diablominer Feb142012. Over 430MHash each card.

Sorry yea.. the 5xxx cards and the 6xxx cards act differently to mem settings.

You might have a hard time finding something to flash the non-reference ASUS DCII cards with...
At least they are equipped with a backup bios, I used mine a lot when I tried various voltage/shaders/memdiff flashes last September.
The bright side is you have the 1 GB versions which translates to less power being wasted by the memory than the 2 GB versions.

Er...  Do you intend on running Windows after the BIOS flash?  If so, why are you flashing the BIOS in the first place?  Windows will allow you to drop the memclocks into the 300 range with MSI Afterburner without a BIOS flash.

If you flash the BIOS on a 6000 series card with a non-standard BIOS, Windows will no longer boot (the ATI driver BSODs).  Linux will boot, however.

I saved 24 watts per 6970 by underclocking the memory to 340mhz through BIOS flashing (Linux rigs).  Not sure how much the 6870s are saving, but they are flashed also.

I was just going to modify the OEM BIOS using RBE, as I have already flashed and reflashed each card, trying to unlock shaders (with no luck).....so that shouldn't be a problem.
I tried OEM Modified BIOS's (that I modified) as well as misc 3rd party.....anything I could find, yet no luck....and they always flashed back to normal once done.

If what you say is true about Windows having a problem with bootup, what I might do is modify the OEM BIOS and leave the 'BOOT' flag clock settings in place, but modify the '3D' flag clock settings...which should take care of bootup problems......so that once mining begins, the clocks will drop automatically for the MEM and go UP for the GPU clocks.

Sound possible ?

The BSOD isn't caused by instability, it's caused by failing a signature check.  The BIOS on the card is signed.  Flip 1 bit, and you get a BSOD.

11.7 drivers don't check for signed driver/bios try it.

Well, it's not like I have anything to risk really....the 6960's have the BIOS switch and can be hot-flipped once booted up, then re-flashed....so as long as I always maintain 1 good BIOS per card to boot with, I can always recover them if something goes wrong.

As a side note:
Many people argued the fact that the switch on these cards (6960 DCUII 1GB) had to do with DVI output etc, but I for one, have confirmed 2 separate BIOS's on my cards after flashing/rebooting etc and compared them using RBE when trying to unlock shaders.

Its way more then that, I bought a wattage reader device, and I plugged my computer into it. And it reads the current watt. I under clocked the memory on my ati 6950 from 1050 to 300 and It dropped 85 watts, which is 42.5 watts/card.

Blew me away, was kinda shocked to see that much of a drop. I did also under volt yielding another 20 watts or so.
Cpu under clocking + under volting did another 40 watts or so on top of that.

Pretty sure you reversed those or screwed up the measurements.  Voltage will make a very substantial change.  Memory will make a smaller one.  If you dropped 42.5 watts per card by underclocking memory, it was *heavily* overclocked in the first place.  Dropping 42.5 watts on a stock card means you shut all of the memory chips OFF...  and then shut off some more memory chips that don't even exist.  :D

The wattage dropped from 380 to 280 on the computer with tweaks, the device is very accurate, and my power bill is a lot less.
So I have to include that it is accurate.

*2X 6870 computer: 380>280*
*2X 6950 computer: 430>330*

How ever It is actually 30 watts per card, and 40watts for CPU.
I did made an error about 42.5 watts.

I measured about 3 times, tried back and forth, etc.
To confirm

http://www.canadiantire.ca/AST/browse/Green/BP/PRD~0528851P/Blue+Planet+Electronic+Energy+Meter.jsp?locale=en
Device I am using.


I was thinking of making a Savinghardware site, instead of a mining hardware one.
Where people can post there numbers on how much watts they saved using a device like mine, or similar.
Maybe someone can make this site, and I can post all my numbers.

I can post my 2X6770, 2X6870, 2X6950.

And I can post three different cpus as well.

It would be interesting to have a site like this.

I have 104 GPUs currently mining and a little under half of them are 6970s (and a few 6870s).  I don't doubt that you can save substantial power by dropping voltage and memclocks.  I've measured it.  I was just saying that your savings on memory clocks alone was off.  The number you reported was more than the chips consume at full load, and Bitcoin mining doesn't even come close to full load.  :)  Power savings from voltage are huge though.