Bitcoin Forum

So I finally figured out how to change the bios so that you can decrease the lower bound of memory clock that aticonfig sees. By default, 58xx cards will only go down to 900Mhz. Here's how:

(Yes, you'll need windows to do this. Deal.)
1. Fire up RBE (http://www.techpowerup.com/rbe/) and load up your stock bios. (I use GPU-Z (http://www.techpowerup.com/gpuz/) to copy it out of my cards)

2. Go to the Clock Settings tab.

3. In the Powerplay states struct list, click and hold on state 1.

4. 3 of the clock info settings will highlight in different colors, red, yellow and green. The yellow one is the one we want. 99% of the time it will be clock info 02, but this step is just to make sure.

5. Change the RAM setting from 900 to 300.

6. If you want to increase the upper bound for Core speed, go to the Additional features tab, and in the "Increase overdrive limit" section, choose method 2, and set the Upper limit GPU to whatever you want. For 5850s, I set mine to 950, just to give some headroom. WARNING: THIS MAY NOT WORK FOR YOUR CARD. For those of you with multigpu setups, flash a card that isn't your primary first to make sure it comes up okay.

7. reboot into linux and check your ranges with "aticonfig --odgc --adapter=all" ....you should see that you can underclock to 300.

8. Enjoy lower temps without decreasing your hashrate!

Thanks for the tips, do you know of any way to do this purely in linux? (Ubuntu)

You can run RBE to edit a bios under wine, and if you boot with a DOS floppy you can flash the bios that way, but there's no pure linux solution AFAIK.

yep, flushing powerplay from GPU firmware would help. you can also put tested/stable clocks directly into firmware, w/o messing with overdrive/afterburner.
just don't forget to save original GPU BIOS[by GPU-Z or something]in case if something go wrong and/or you drop mining/want to use GPU for personal purposes[w/o PP and w/more fan noise its not so comfortable 4 some users] and buy PCI video card in case if you broke you BIOS/Brik GPU.

You so rock!  Thanks

If you want to stay completely in linux just use AMDOverDriveCtl for each of your display devices.

http://sourceforge.net/projects/amdovdrvctrl/ (http://sourceforge.net/projects/amdovdrvctrl/)

This will allow you set the memory clock down and you don't have to mess with windows.

Honestly? I've never gotten that to work reliably. The lower bound has always been restricted to the same as aticonfig.

Maybe this stopped you?

AMDOverdriveCtrl: /usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.14' not found (required by AMDOverdriveCtrl)

Anybody has a solution for this?

It won't. BIOS-enforced limit, so your solution is valid. What card have you got then, having to raise the max. core clock to 950? Thought they were pretty much all limited at 1000+ (at leasy my Asus card is).

Could you also raise the voltage while doing this?
Which clock info do you do?

Excellent guide... so what cards are you running and what are your paramaters and hash rate....  Thanks...

I haven't tried personally, but you're supposed to be able to change the vcore as well. If you happen to have a 5850 reference card, also check out http://forum.bitcoin.org/index.php?topic=10228.0, I'd love some feedback.

That's what I got too. Some research told me that AMDOverdriveCtrl was compiled with a version of libstdc++ that wasn't available on my version of ubuntu (10.04). I couldn't find a way around it.

Does anyone have any measured benefits for setting the memory speed way down say from 1250 to 300-400.  Is all the hassle worth it?  In terms of power saving?  Heat reduction?  Being able to bump GPU up even more (if already overclocked to the max)?

I got AMDOverdriveCtrl to run on Ubuntu, but it doesn't seem to work (mem clocks still won't go below the limits shown in aticonfig).

For some people it raises hase rate, for others it doesn't. But generally, it will lower temps.

Installed Wine on my Ubuntu 11.04 but it would not run the RBE executable... Any ideas?

You have to do it in Windows.

Get winetricks (http://wiki.winehq.org/winetricks). It's a script that fetches various packages to make running things easier.

Also, giving credit where it's due, use this (http://blog.ryanc.org/?p=8) blog entry to do the right thing. Unfortunately, atiflash under freedos has never worked for me personally, because I keep getting Hyper Transport sync flood errors. I have no idea how to get around that.