Bitcoin Forum

Hi, im not exactly a newbie however I'm finding it hard to find any information solving this problem very much anywhere else.
I have a mining rig, (2x ATI HD6870). the first card is connected to a pcie 16x slot and the other a modified 1x slot.
They are adequately separated for cooling. non crossfire.
its running linuxcoin final from a usb and have set up headless mining.
i have tested this in another machine running windows and the same 2 problems.
The problems are as follows:

device 0 heats up much more than device 1.
this problem is not present when only one card is used. (also i think this problem might be related to the next one)

aticonfig can't under clock the memory to below 100mhz below the core clock. if it is it jumps back to the maximum memory clock (and i believe it causes the overheating described in the previous problem).
this problem is not an issue when only a one card is used.

same issues when using msi afterburner on windows 7.
Does anyone have a solution to this problem? I'm willing to do anything but keep them in separate machines.
Thanks

Probably a dumb question but have you disabled ULPS?

From what I've heard from others, to successfully underclock in Linux you may have to flash the card bios. I've stuck to Win7 to avoid that.

In windows, MSI Afterburner is not always enough to properly underclock. After many hours of experimenting, I now use a combination of several underclocking tools...it seems like different tools may be changing different settings. (The cards store settings for several different modes of operation.)

The first tool is GPU-Z. This will give you the true current clock values on the cards, while many of the OC tools will give you false values (settings that might not have "taken", or they might be reading values for a certain mode that the card is not currently operating in)

The next tool is Phoenix Rising (now called AOCLBF or something like that...no idea why the author decided to change it to such a hard-to-remember name.) I start that up with saved clock values. This doesn't change card clocks (yet), but changes some of the settings.

After that, I open Sapphire Trixx. It will read the values Phoenix Rising loaded, and although these still haven't actually set the card clocks, if you click on the Overclocking tab, change the values slightly and then change them back and click "apply", it will allow Phoenix Rising to set them.

I go back to Phoenix Rising and click Set Clocks for each GPU - this time the memory and gpu clockspeeds should be set properly. You can check in GPU-z. This also resets the fans to some lower setting.

Then I load MSI Afterburner, and it will dynamically adjust the fan speeds. I do this because the fan speeds, even when set with the other programs, often get reset to some factory setting which isn't sufficient for stressing the GPU 24/7 for months on end.

Sometimes MSI Afterburner is enough. It appears to depend on the brand and model of card. I've had to do this for several of my machines that have Sapphire and MSI cards. Machines with only XFX and Asus 6870's seem to work with just Afterburner.

Hope that helps, good luck.

I've tried using other tools under windows and i now can't use the windows machine (it was my housemates machine and only to be used for testing.

Whats ULPS?


So I've done a little bit more reading around and i have found one topic on flashing a customised bios to the cards to set a hard value on the memory clocks.

https://bitcoin.org.uk/forums/topic/330-hardware-how-to-get-400-mhs-from-cheap-1gb-6950s-in-linux/
(down near the end)

This seems to be the simplest way to do this. especially if I'm using linux which as i understand doesn't check the signed hash values from the bios.
Ive also sent a ticket to my card manufacturer to ask them whether they can help me out a bit (not really expecting any real help...)

over the next couple of days i will give this a go and hopefully write up a more detailed report on the success of flashing the bios on the cards and whether they work under linux or windows.

6000 series cards can't have memory clock reduced to less than 150 below core.  Trying to do so will result in memclock running at stock.  You should be able to get it to take 150 Mhz below though.  So for example if core is 850, you could run at 700 Mhz clock.  Trying 700 clock though will result in memclock actually running at full stock

5000 series and 7000 series don't have this issue.  Some have reported success flashing a custom bios but it is possible to brick a card if you don't know what you are doing.

Thats the problem that i was describing...
I'm now aware that the 6000 series are limited to having a memory clock 100mhz below the core clock.
once i get home i will try using radeon bios editor to try and set the memory clock to 340mhz, and report back once I've done this...

and yes its possible to brick a card doing this but i would rather have at least 1 card working at the rate that i want it to (ill start with just one, if i brick it i still have another one) than have both cards crippled in power usage and heat output by their memory clocks.

It is -150Mhz not -100Mhz.  It might be a typo but you keep making same claim so just wanted to clarify.  Lowest meclock = core clock - 150.

linuxcoin:
for 6870 memory underclocking you have to edit the bios: http://www.techpowerup.com/rbe/ (http://www.techpowerup.com/rbe/) (fully read and understand the tutorial!)

w7:
use latest afterburner beta: http://download1.msi.com/files/downloads/uti_exe/vga/MSIAfterburnerSetup220Beta.zip (http://download1.msi.com/files/downloads/uti_exe/vga/MSIAfterburnerSetup220Beta.zip)
and tweak configfile with:

EnableUnofficialOverclocking   = 1
UnofficialOverclockingEULA   = I confirm that I am aware of unofficial overclocking limitations and fully understand that MSI will not provide me any support on it
UnofficialOverclockingMode   = 2

google that, I don't remember exactly how to tweak it proper.

this worked and still works for my 2x msi r6870 twin frozr rig

Do at your own risk!

I can verify that this works (editing the BIOS)
I can also verify that it works for the GIGABYTE HD6870 Super Overclock edition...
I also edited the fan curve while i was there.

I have the same problem with my 6870's, the memory doesn't underclock, run it @ 1050 Mhz  :-[
But is does undervolt  :)

I fixed my problem, flashed my XFX bios to BARTS stock, now I can use Afterburner to underclock memory. :)

Can you tell me where to find that stock bios, gone do the same. I hate 6870's they run way to hot.
5870's are way better! run easy @ 950/300 without any cooling mods.
I already put AS5 on my 6870 instead of the factory stuff and still they run way hotter than the 5870's

I found the links here: http://forum.overclock3d.net/index.php?/topic/31504-6870-9401150/ (http://forum.overclock3d.net/index.php?/topic/31504-6870-9401150/)
All the files needed should be here: http://www.4shared.com/file/cgm9d0l6/6870_BIOS_MOD.html (http://www.4shared.com/file/cgm9d0l6/6870_BIOS_MOD.html)

My 6870's will only do 100Mhz mem-diff. (Diamond/Reference).
My 6950's will do 150Mhz mem-diff. (1GB Non-Ref).

Reading this helped me a lot. Thank you!

The W7 method worked for my single 6870. GPU-Z & MSi both say I am running currently at 1021/525 [291 Mhash]. I still don't have access to the voltage, but that's okay. How far should I take my over/under-clocking?

EDIT: Without touching voltage, It seems that I max out at 1030/300 @ 70-75C Fan @ 50%