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for all you guys that are claiming that you underclocked the memory of your HD6000 series cards to lower temps and power consumption, well i just found out the hard way that the memory on these cards do not actually underclock. you may be able to manually set the memory speed lower in MSI afterburner or sapphire trixx, but the settings don't actually "stick". you can actually verify with various sensors that these settings don't actually work. the HD5xxx series cards underclock wonderfully, but there's something about the 6xxx that won't allow this. i have tested this with 6570, 6970, and 6950, they all can't underclock the memory.

refer to his example screenshot i took of the new 6950 i just bought. you can see in the GPU-Z info that default memory is 1250mhz, and supposedly the speed is currently unclocked to 300mhz. you can see in sapphire trixx and the setting panel of MSI afterburner that i set the memory clock to 300mhz (after unlocking the config file of course). now, if you look at the GPU-Z sensors tab and the hardware monitor graph of the MSI afterburner, you can see that the memory is still actually 1250mhz, regardless of what i manually set the memory to. so on these 6000 series cards, you can overclock the memory, but not underclock it.

if you underclock your 6000 series, please check your sensors again to verify this, and post back here whether this is true or not. and i challenge anyone to prove me wrong, or find a workaround for this "lock".

http://img691.imageshack.us/img691/1204/screenshothcj.png (http://imageshack.us/photo/my-images/691/screenshothcj.png/)

I have with my 6870.

I think your computer might have some issues. Perhaps Afterburner and Trixx are interfering with each other?

Mine underclocks just fine according to gpu-z's sensor graphs.

so you verified that it underclocked fine? or did it not work also?

i verified this independently from each other by having only either trixx or afterburner open, and it's the same results. what card are you running? and are you able to take a screenshot of the sensors?

It worked fine and the Afterburner stats showed it. MHash/s went up and temps went down.

what drivers and OS are you guys using?

Catalyst 11.6 on Win7 64-bit.

I can confirm what Haploid has just mentioned,you cannot underclock but it seems to be on the 69xx series.I have a 6900 series card and can confirm it does not allow the memory to underclock.This could be locked in the bios as I've tried using tray tools to underclock which served me quite well when I had a 5770 and that definitely underclock on the same system.

This is the first i've seen someone claim it can't be underclocked at all although i would belive it can't be underclocked as far have you tried something like only underclocking it 50 or 100mhz just to verify? as for KKAtan what card are you using the 6770 and 6750 are only rebadged 57xx cards.

It can be underclocked, its a bug in gpuz.
Everything else will show its underclocked, and doing bandwidth speed tests on the card shows it to be underclocked.

That's not even remotely true. Shittily programmed software can artificially limit the underclocking for people who don't know what they are doing, but the hardware itself is fine with it.
The graphics cards will underclock all the way until the computer crashes, somewhere between 0-100 mhz. Some 1st generation gddr5 controllers on certain Cypress revision will crash at certain specific frequencies, yet you would be fine by staying 1 mhz above or below these hotspots.

You require screenshots.  ???
....Am I untrustworthy or something?

Some basic googling should be enough to prove what I'm saying.
http://www.legitreviews.com/article/1488/17/

69xx can be underclocked, but only to about 125 MHz less than GPU clock. try to uc less than this and temps rise. look a bit harder and you'll see that mem clock has reset back to max. there are plenty of threads here addressing this issue.

Seems to work fine for me on my 2x 6950's

https://i.imgur.com/04dEk.png

I was having the same problem.  I flashed the bios to lower the maximum clock to where I wanted and now it works fine.

and your temps are still 72? Mine are 69 for a 6970 at 880/780. It doesn't really look like that underclocking is working to me.

Yeah, the case is closed (with 2x120mm fans on the side) in my basement which is about 85F ambient right now (I live in PA, hella heat wave!)

Usually they sit lower than that

ok, but if they were underclocked I'm fairly sure you be a bit cooler. Try a test - as is, then back to max. Run max for a few hours, post the two temp diffs. I'll be really interested in your answer since I haven't been able to uc mem very far before it reverts to max.

it seems like it's a hit or miss with the cards you get. from what i've seen so far, there has been more people unable to underclock the memory to the 300mhz range than people that have successfully done it. just like with flashing a 6950, not all of them are flashable because they're hardware locked. and the ones that could be flashed, not all of them are able to unlock extra shaders to a 6970. it's just the luck of draw, but you make it seem like anyone not being able to underclock the memory is really that incompetent. it's pretty straight forward to do, no? just like with the HD5xxx series, all you do is pull the memory slider lower or enter values in small increments. however, on all the ones i've tried, it just reverts back to default memory clocks. this was done on all updated software versions and verified with different sensors. i looked at the power consumption and temps, and it indeeds corresponds to stock memory speeds.

btw, your link to legitreviews.com proves nothing. ya sure the core and memory underclocks iteself when idle, but once you put a load on it, they both default back to normal clocks. that article did NOT manually  test a memory underclock at load like you said. you should try reading that article yourself before making a reference to it.

so are you suggesting that it's a bug in both GPU-Z and afterburner sensors? because in my screenshot, they both agree with each other, so i doubt they're both wrong.

Well, I read your thread title and your first post, you seemed to imply that this was true for all 6xxx cards.

It was supposed to prove that all videocards are capable of clocking down to 150 mhz at the very least.

All I can say is that I have 6870 from MSI and 6950 from Sapphire. All of them underclock.
If this is indeed some hardware lock or bios lock, maybe the people who have this problem should post which vendors have this issue.

So which company is your problematic cards from? XFX? HIS? Asus? or?

sapphire

Ran a test.. I don't think I need to run it very long at all. The temperature difference was immediate. I waited until things stabilized then took some screenshots/pics of kill-a-watt. Here are my results. (Also, these cards are Sapphire http://www.newegg.com/Product/Product.aspx?Item=N82E16814102921)


Underclocked memory results:
https://i.imgur.com/X6mYk.jpg

Default memory results:
https://i.imgur.com/gBEJT.jpg

Same experience here - XFX 6870 (the reference design). Can "try" to underclock both in afterburner or TriXX, but the actual frequency is still high..

The reason why you can't lower the memory clocks is because you have to disable AMD Overdrive in CCC.  The problem is that the 69xx series need Power Control Settings set to 20% for optimal performance.  Some cards can bypass this (ex: MSI 6970 Lightning) but others cannot unless AMD Overdrive is enabled.

Thank you you heaps for taking the time to do that! You are totally right. Now if the 'disable AMD overdrive' dude is correct, I just have to figure out how to do this under Linux and maybe my gf and my power company will hate me a little less.

Not a problem! :)

I have 3x 6950's coming here on Monday/Tuesday and I'll be running linuxcoin on this box. Ill let you know if run into a similar issue.

Lots of Linux overclocking info here:
http://www.linuxcoin.co.uk/wiki/index.php/Overclocking (http://www.linuxcoin.co.uk/wiki/index.php/Overclocking)

I've got two 6970's and was able to get their mem clocks down to 755.  Any lower and it would shoot up to max when under load.

So you don't know how to do what this guy did either?

It underclocks just fine. Unlock AB, it will stick at any number. Id advise against it though...

i have no idea what you mean. how are you underclocking memory for a 69xx series on linux and why do you advise against it?

Win 7, but if win can do it its not the card's fault.

As for why I advise against it, see http://forum.bitcoin.org/index.php?topic=31584.0 (http://forum.bitcoin.org/index.php?topic=31584.0)  :(

Eh I'm pretty sure clock speeds aren't going to brick your card. Voltage and heat will do it.

That being said, I put together my 3x 6950 setup with linuxcoin and ran into the same problem. I couldn't get the memory to clock under core - 100. I disabled CCC Overdrive and it didn't help. People said Catalyst 11.6 fixed that (maybe it did with 5000 series cards) but it didn't do me any good.

The only guys who seemed to be getting anywhere were the ones who flashed the bios to another manufacturers (I think Asus) or modifying the bios to change the min/max speeds.

http://forum.bitcoin.org/index.php?topic=19776.msg290674#msg290674

I have a Asus 6950 DC2 1GB and I noticed the memory doesnt under clock correctly when trying to use programs such as afterburner and so forth. But ati tray tools allows me to take the memory all the way down to 150mhz or lower...and confirmed it w/ gpuz sensors and power usage substantially dropped.