Optimising 6950's - Help required please

dreadhead

Hi Folks,

I have two ATI 6950’s in my rig. I am trying to configure Cgminer for better performance.
Crossfire is turned off in the CCC.
I am running CC 13.4
My cards are running at stock settings. (see attached for gpu-z)

Currently I can only seem to mine using the following settings:

cgminer.exe --scrypt --intensity 11
These settings give me 149kh and 144kh on each respective card

If I turn up intensity to 12 the mining becomes unstable, I get a 246kh and 239kh rate but error messages pop up occasionally saying:
GPU0: invalid nonce - HW error
and
GPU1: invalid nonce - HW error

If I turn up intensity to 13 these errors become much more prevalent.

I read about setting some other values such as --shaders 1408
As soon as I do this cgminer opens then immediately crashes.
Forcing a --thread-concurrency to x5 the shader value as suggested makes no difference and also results in a crash.

I am sure I can get much higher hash rates out of these cards so any suggestions would be welcome.

Thanks

[attachment deleted by admin]

DaMooMoo

[code]ALLOC_PERCENT=100
GPU_USE_SYNC_OBJECTS=1
cgminer --scrypt -d 0 --url xxxxxxxxxxxxxxxx --user xxxxxxxx.x --pass xxxx --gpu-engine 900 --gpu-memclock 1000 -I 18 --thread-concurrency 8192[/code]

These are the setting I use on my 6950. Get about 445kH/s. you should get up to 475kh/s with tuning of gpu-engine and gpu-memclock.

Edit: also downgrade to cat 13.1. I was getting cgminer crashing with 13.4 drivers.

dreadhead

Thank you both for the detail.

I will experiment and report back.

dreadhead

I made it!

810Kh/s

I still have some optimising to go, but for those interested I achieved this by disconnecting the crossfire bridge and using the ATI cleaning tool to clear off all drivers.
I then tried many variants of drivers all of which caused cgminer to crash on opening with the exception of 12.8
Finally I was able to crank the intensity up to 18 and the cards have been slogging away for an hour now with zero errors.

Thanks to those who suggested fixes and I wish everyone else lots of luck.

DaMooMoo

[quote name=“dreadhead” post=“20634” timestamp=“1373317556”]
I made it!

810Kh/s

I still have some optimising to go, but for those interested I achieved this by disconnecting the crossfire bridge and using the ATI cleaning tool to clear off all drivers.
I then tried many variants of drivers all of which caused cgminer to crash on opening with the exception of 12.8
Finally I was able to crank the intensity up to 18 and the cards have been slogging away for an hour now with zero errors.

Thanks to those who suggested fixes and I wish everyone else lots of luck.
[/quote]

I’m really happy with my Gigabyte HD6950. I purchased it second hand from ebay for $100 AUD and hasn’t missed a beat. I currently have engine set to 955 and memory set to 1250 and its cranking out 470kh/s. Its also running surprisingly cool with temps maxing at about 73c in open air with a 25c ambient. This highest Ive had it is 475kh/s but drivers eventually crash.