CGminer / linux - changing 7950 voltage below 1.125V

[HuuHachu]

Hello,

I have a sapphire 7950 OC dual-X (11196-19 flavor) and I am running ubuntu 13.4 with the last stable drivers.

The stock voltage for this card is 1.25V.

CGminer (3.1.1) cannot lower the voltage below 1.125V, where triXX can set whatever value I want to try.
By the way, under windows CGMiner can't go below 1.125 neither ... but using triXX in parallel works.

Does someone know a way to lower the voltage in my linux setup ? (from my tests under windows, 1.05 or even 1.0 would do well - and 40W less)

My card has a second bios, but it behaves similarly and with an even higher stock voltage ... 1.169V minimum if I recall correctly.

I'm considering using the bios from another (older ?) card, but I'm not sure which one would do ... (brand / model / ... ?)
And changing the bios is kind of last resort ... I would prefer a software way, especially since triXX is working !

Thanks for your advices !


PS: cgminer not changing voltage below 1.125 means that it says "ok" when I put something lower, but still indicate 1.125 afterward and the power consumption does not move one inch.  (It does with triXX)

[1715153118]

1715153118

[MrBilling]

You need to flash to a lower V BIOS.  You cannot change the V in Linux.

Look at the link in the post I linked below.  You down load it from the link and then flash it using ATIFlash.  I advise to flash it with the bootable DOS USB method.  You can do it with ATIWINFlash but the DOS way is a lot safer.

And unless you flashed it to something different both of your BIOSs should be the same stock BIOS.  The second BIOS is there in case you mess up the first one you can switch to the second one to recover the first.

The BIOS below lowers the V from the stock 1.25V to 1.09V.  I have my BAMT rigs running this BIOS and they run 1100/1500 at 1.09V.  Very stable.

https://bitcointalk.org/index.php?topic=205406.msg2239094#msg2239094

[HuuHachu]

Thanks for your response. This is the solution I was suspecting I would have to resort to ... As a bonus the thread you linked gives a link to a bios that should work (they have dozen just for saphhire 7950 from which I could not choose on techpowerup.com ^^)

Will test and update my post later !

[HuuHachu]

Damned !

I bricked my 7950 (I managed to flash wrong bios in the two slots ! silly me)
Hopefully I found an old S3Trio PCI board and was able to use it to boot and flash back my original bios.

I dont know what sapphire did to this particular board, but no bios listed on techpowerup seems to be compatible .. no luck

[MrBilling]

Only flash in DOS using a bootable DOS USB stick.  Do not flash in Windows.


Do not flash your number two BIOS.  Only use your number two BIOS if you mess up the first one.  Make sure you make a backup of your original BIOS using GPUz.

[HuuHachu]

In fact flashing using ATIWinFlash (in command line) worked well in itself.
The problem was that I did not understood well the procedure to flash-back the first one after putting a non working one.
First time I tried to flash, I had booted on bios 2 (the one I do not normally use) and it told me it was write protected.

I falsely deduced only the first one could be flashed. I rebooted on bios 1 and flashed it.
After discovering it was not working, I rebooted on bios 2 and reflashed ... but forgot to press the button while the computer was already booted up ... and ended flashing another non-working bios

It was kind of un-natural to me to use a jumper on a powered board ... Besides, the first complain about write protect was in fact due to the flashing software not running in administrator mode.

By the way, I managed to get my board working again by booting on an old PCI card, so no harm in the end, but still some cold sweat ^^

Only flash in DOS using a bootable DOS USB stick.  Do not flash in Windows.


Do not flash your number two BIOS.  Only use your number two BIOS if you mess up the first one.  Make sure you make a backup of your original BIOS using GPUz.