Underclock memory on 6990 Linux?

[martok]

Hello,
Has anyone successfully underclocked a Radeon 6990 under Linux using amdoverdrivectrl? If so, would you mind sharing your overdrive profile?
No matter what I do, an underclock doesn't take. Here's what I currently have:
<?xml version="1.0" encoding="utf-8"?>
<OVERDRIVE_PROFILE>
<PERFORMANCE_LEVEL level="2" gpu="83000" mem="30000" voltage="1120"/>
<PERFORMANCE_LEVEL level="1" gpu="50000" mem="125000" voltage="1000"/>
<PERFORMANCE_LEVEL level="0" gpu="25000" mem="15000" voltage="900"/>
<FAN_SETTING percentage="auto"/>
<FAN_CTRL enabled="yes"/>
<FAN_CTRL_CURVE type="0"/>
</OVERDRIVE_PROFILE>

[ius]

Check with aticonfig --odgc. If your desired memory clock doesn't fall within the range shown, you'll need to edit the BIOS I'm afraid..

[martok]

Check with aticonfig --odgc. If your desired memory clock doesn't fall within the range shown, you'll need to edit the BIOS I'm afraid..

Does amdoverdrivectrl not support the 6x series yet. the method above works fine on a 5970 though aticonfig doesn't.

[martok]

After much fiddling, I discovered that a 6990 underclock can in-fact be done under Linux using amdoverdrivectrl. The problem with my profile above was that profile 2 had memory at 300 and profile 1 had it at 1250MHZ. It appears that the memory clock on a higher profile cannot be lower than one on a lower profile. So, the following profile worked for me. Feed it with something like:
amdoverdrivectrl -b -i 0 6990.xml
<?xml version="1.0" encoding="utf-8"?>
<OVERDRIVE_PROFILE>
<PERFORMANCE_LEVEL level="2" gpu="83000" mem="30000" voltage="1120"/>
<PERFORMANCE_LEVEL level="1" gpu="50000" mem="30000" voltage="1000"/>
<PERFORMANCE_LEVEL level="0" gpu="25000" mem="15000" voltage="900"/>
<FAN_SETTING percentage="auto"/>
<FAN_CTRL enabled="yes"/>
<FAN_CTRL_CURVE type="0"/>
</OVERDRIVE_PROFILE>

Hopefully this is of use to someone.

[martok]

I've done this before but the card itself appears to ignore the settings.  I have 6950, 6970, and 6990 and they all seem to blow through the "peak", whereas a 5870 follows the clocking request quite closely.  Do you actually get the 69xx to clock down the memory when it's under load?

Ah, you are quite correct. The peaks show lower but the actual clock doesn't come down. Do Windows users get this as well?

[IlbiStarz]

Nope, but I'm also getting that peak problem on my 5850. (Linux)

[martok]

Nope, but I'm also getting that peak problem on my 5850. (Linux)

Did you underclock via RBE? I wonder if an RBE underclock would fix this. I don't have a windows install to test that, though it's tempting.

[molecular]

I've done this before but the card itself appears to ignore the settings.  I have 6950, 6970, and 6990 and they all seem to blow through the "peak", whereas a 5870 follows the clocking request quite closely.  Do you actually get the 69xx to clock down the memory when it's under load?

Ah, you are quite correct. The peaks show lower but the actual clock doesn't come down. Do Windows users get this as well?

I can verify this problem. Using my self-made tool that uses adl-calls to set the clocks of all 3 performance level.

This method works on a 5970 and it works to set the Peak clock, but the card simply ignores the peak and aticontrol --odgc reports "Current Clock 1250 Mhz, Peak Clock 150Mhz".

Damn you, amd

[darkpandora]

amdoverdrivectrl dont work on 6990, you cannot underclock memory. have anyone had any luck with underclocking 6990?

[molecular]

I've done this before but the card itself appears to ignore the settings.  I have 6950, 6970, and 6990 and they all seem to blow through the "peak", whereas a 5870 follows the clocking request quite closely.  Do you actually get the 69xx to clock down the memory when it's under load?

Ah, you are quite correct. The peaks show lower but the actual clock doesn't come down. Do Windows users get this as well?

aha! just found some info in another post: https://forum.bitcoin.org/index.php?topic=18107.msg229587#msg229587

apparently you can underclock ram down to 100Mhz below core clock.

EDIT: actually, it seems here, I can go down to 800Mhz