Bitcoin Forum

Hi,

My 6970 shows some weird behaviour when it is overclocked. Looking at the gpu clock graph in MSI Afterburner it will flip up and down between stock and the higher clock. This actually leads to worse performance than at stock clock.

Has anyone else seen this? Found a solution? Does it mean the card has to be flashed?

Thanks!

Edit: It's not a cooling problem, it never goes above 70 degrees. The PSU is a Corsair HX750.

What mining software do you use and what settings (flags)?

Tested with poclbm using various flags, currently using -w 128 -v

Also tried phoenix using various flags, for example VECTORS BFI_INT WORKSIZE=64 -k phatk

poclbm is what I'm currently running. No matter what settings I tried the same result occurred. I run with -f / AGGRESSION set to use ~95% of the GPU, since I use this computer day-to-day.

I use a 6970 as well at 960MHZ GPU and 760MHZ RAM.
I noticed some minor flips as well but not really that much as you are describing.

The best results I've got with Phoenix 1.50 (started via GUIMiner) and the following extra flags:
-v -k poclbm WORKSIZE=128 VECTORS BFI_INT FASTLOOP AGGRESSION=11

This brings me to ~405 Mhash/s for the GPU

I am using Catalyst 11.6 and ATI SDK 2.4
(You should disable Catalyst based Overclocking in the Control Center)

Hope this helps.

Also using 11.6 and 2.4. I hadn't turned off overdrive, but it didn't help :(

Can't go beyond 900MHz with my ASUS 6970.

Best results (GUIMiner)

poclbm.exe -v -w128

I'm getting 380MH/s.

Yep, running ASUS here too. I can get 365-370 if i really push it, but never more than that.

I had ~385 too with GUIminer by default. I've downloaded and updated the Phoenix miner in GUIMiner. The one which comes with it is 1.48 and the latest version here in the forum is Phoenix 1.50 which is faster.

Well I never did use GUIminer but I might have an old version of Phoenix, I'll check it out :)

I found that I needed to use CCC to up the voltage 10% on my 6970.  Using MSI Afterburner (on an MSI card) did not seem to work when adjusting voltage.  See here:
http://forum.bitcoin.org/index.php?topic=19488.0 (http://forum.bitcoin.org/index.php?topic=19488.0)

I found another thing.. I need to set clock speeds to values of 10x.. So 950MHz, 960MHz, etc..
If I use other values, the driver crashed..

I consistently loose 10% on my 6970 Lightning if I use VECTORS (or -v in poclbm). At stock clocks (940MHz, 1375MHz) I get 386MH/s, and I haven't been able to tweak it any higher than that.

Ubuntu 10.10
SDK 2.4
Driver 11.3
Phoenix 1.50

Thank you! This did it. Now getting 400mhash at aggression=7. I googled a bit about power control, it's not actually a direct voltage control. It just limits the power draw of the card. So if the card uses more power than the power control setting, it will throttle to keep it down. So there should be nothing to worry about when increasing this, as long as the temp is fine :)

Ah, but now I have a different problem. With overdrive enabled, my 5850 is limited to 775 mhz, even in afterburner it would seem (doesn't matter if I set the clock higher, it doesn't go higher). Since clocking this gives a bigger gain, I'll have to stick with overdrive off. Any solutions to this?