This is my first go at doing any GPU overclocking and it's been a bit rough so having now managed to figure out how to at least change the settings I need with my card I would post it in case anyone else is in the same boat.

My card the Sapphire 6950 2Gb Dirt3 edition seems to be rather difficult to modify the Voltage on along with the clock speeds without glitching. ALL programs other than AMD's own Graphics Overdrive in CCC caused graphical glitching whenever setting clock speeds (even when setting them to the stock settings!). That includes Sapphire's own Sapphire Trixx (4.1.0 and 4.3.0).

Thanks to this board I found a thread on unlocking the caps set by CCC and using MSI Afterburner the official way. This allowed me to overclock using MSI Afterburner without glitching as well, but unfortunately still not set the Voltage. MSI afterburner even with cfg tweeks would not allow me to set the Voltage.

Eventually I found another thread showing a method of modifying the Voltage by manually editing the CCC profile. I thought I would post the steps here.

1. Completely close CCC. I achieved this by killing CCC.exe with Task Manager and making sure it didn't respawn.
2. Use Explorer to go to "%AppData%\..\Local\ATI\ACE" (for my system this is "C:\Users\myusername\AppData\Local\ATI\ACE").
3. Edit "Profiles.xml" with a text editor.
4. Find a section that looks like this:
   
   Code:

   <Feature name="CoreVoltageTarget_0">
       <Property name="Want_0" value="900" />
       <Property name="Want_1" value="1020" />
       <Property name="Want_2" value="1100" />
   </Feature>

   where the "_0" at the end of "CoreVoltageTarget" can be the name of your card. I found I had 2 of these sections in my Profiles.xml file and I wasn't sure which one set my card so i modified them both.
5. Change the value of property "Want_2" to the voltage you require so 1.180V would be:
   
   Code:

       <Property name="Want_2" value="1180" />

   the "Want_2" appears to be the high performance setting for in games or benchmarking (can't be more certain than that I'm afraid).
6. Start up CCC again. (edit) Possibly requires restart instead of this step - to be confirmed.
7. Apply Overclocking settings in Graphics Overdrive and apply.
8. Check your Voltage settings while benchmarking for example using MSI Kombustor. It should now be set to your new value.

Phew! That should be it.

Now that's some persistent OCing. good work that man.

or you could just fllck the bios switch on the card to unlock overclocking options with trixx, and maybe a 1536 shader bios too.

Nope, doesn't unlock voltages for me. I have to admit that I hadn't thought of this, I had switched back to using the basic BIOS setting some time ago to see if some trouble I was having was its fault. However testing the BIOS with the unlocked shaders on my card now still doesn't give me Voltage control. I hadn't really thought of the BIOS route is there any way to unlock Voltage control in Afterburner by modifying my BIOS, say with RBE?

Also I raised the question of why Sapphire Trixx has disabled Voltage control in 4.3.0 with Sapphire who said this:

Dear Sir
Sapphire follow AMD rule, so we change to power limit on new version. You can rollback to previous version. Sorry about that.
Regards

Click to expand...

(edit) I wouldn't mind them switching it for Power Limit if it behaved sensibly and managed voltage control for you, instead it leaves it stuck on 1.10V no matter what setting you use. Looking at my BIOS volt settings that's actually lower than the boot Powerplay state.

Hi there I've been doing some playing around since I read this thread.
So bear with me but these are my findings. I've had this reference 6950 unlocked and clocked for almost 2 years now so forgotten some things. I apologise it seems that maybe your card has a locked voltage controller chip. I'd try msi afterburner 2.1.0 open the MSIAfterburner.cfg and then reword the

[ATIADLHAL]
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 = 1
AccessibilityCheckingPeriod = 0

once afterburner opened goto settings and enable Unlock voltage control restart afterburner.
Use gpu-z tp monitor if your v-core is increasing to what you set it to in afterburner makign sure ccc overdrive is disabled.


I was on 12.4a hotfix catalyst for a long time I skipped 12.6 and eventually went with 12.8.
This glitching was noticeable on 12.8 whenever I used presets on my trixx,
I have 3 presets 800/1250/ 880/1375 and 940 1375 the screen would flicker between
changing each preset and the voltage would stick on my highest overclock, the gpu clock
would be 500mhz and the ram full speed even though the gpu had no load on it.!!
If i lowered to the 800 1250 one, the idle would then be 450mhz/ ram 1250 and the gpu v-
core 1.110v. These seems like the pstat 2 for video watching etc, idle should be 250/150
at 0.90v

So I played with some eariler catalysts and some later and this is what I discovered.
Trix versions 4/ 4.01/ 4.02 4.10 and 4.30 enable gpu voltage change on 6950s.

Trixx version 4.30 has a board power li feature and the vddc option is under it they havent removed it, just need to scroll down.

This is what the catalysts do with any of the trixxs
Cataylst 12.4a and trixx work absolutely spot on when overclocking, it idles properly and theres no flickering at all. Just an older driver so some game bugs may be present?

Catalyst 12.6 and trixx work well when overclocking, it does occasionally flicker only when changing presets, and very rarely sometimes the idles clocks get stuck in video mode.

Cataylst 12.8 and trixx don't work well when overclocking, The card will not return to a proper idle state and if a high overclock set then it will stick to that.

Catalyst 12.10 12.11 and trixx dont work well when overclocking,
The screen constantly flickers with any overclock, it does idle properly but internet scrolling and general usage is poop.

Your ccc way seems interesting does it work for you? and what catalyst are your running?

akamikeym said:

Nope, doesn't unlock voltages for me. I have to admit that I hadn't thought of this, I had switched back to using the basic BIOS setting some time ago to see if some trouble I was having was its fault. However testing the BIOS with the unlocked shaders on my card now still doesn't give me Voltage control. I hadn't really thought of the BIOS route is there any way to unlock Voltage control in Afterburner by modifying my BIOS, say with RBE?

Click to expand...

I have played with rbe but it wasa taking ages to get it how I wanted, when trixx offered an easier custom fan profile .As you have dual bios I'd say have a play, but then if theres an easier way like you've mentioned and it works then just stick with that.

Davedree said:

Hi there I've been doing some playing around since I read this thread.
So bear with me but these are my findings.

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 = 1
AccessibilityCheckingPeriod = 0

Click to expand...

The part in bold is why you have flicker problems Dave.

Hi Davedree,

Yes I'm an idiot, you're right. I can't believe I didn't move the scroll bar in Sapphire Trixx down. For some reason I thought it was just an issue with their big graphics not fitting into the container they'd given it.

I've not been able to find a copy of Afterburner 2.1.0 to try it out but 2.2.5 and 2.2.5 betta both refuse to allow Volting on my card (I've not idea why since Sapphire Trixx at least allows some). My method seems to work as long as I restrict myself to using CCC and don't use AB which sets the profile Voltage back down to 1.10V.

I wouldn't have minded getting a Voltage set in my BIOS as I use Linux as well and it would be nice for the Overclock to hold for both, as I do for my CPU but it seems to refuse to work. My card's BIOS and RBE doesn't allow me access to GPU Registers so I can't set the Voltage in there. I've tried setting it by hand in the Voltage section of Clock Info 03 which appears to correspond to my high performance profile, but it has a weird default of "---" and just bombs out when booting windows (after the windows logo animation). For some weird reason Linux will boot fine with that BIOS but who knows what it's doing.

LtMatt said:

The part in bold is why you have flicker problems Dave.

Click to expand...

I don't use ab for overclocking though, always used trixx for years and since after 12.4A, trixx doesnt work properly. I've been reading your official guide so gonna give ab a go will let you know how i find it.
The problem is amd buggered up their catalyst drivers, because we had this idle problem on very early drivers back when the 6950/70 came out.