for HD6950, a user on Github advises to use worksize=32 and multi_hash=864, one one thread.
Take a look at the HD6000 user topic here:
https://github.com/jceminer/cn_gpu_miner/issues/26{ "mode" : "GPU", "worksize" : 32, "alpha" : 64, "beta" : 8, "index" : ...., "multi_hash":864 }
also try with worksize=16 and 8
Hi JCE, I'm testing on my 3 - 6950 card with 0.33b4 /0.33b6 i've also try 8 and 16 worksize. But i didn't understand whats is alpha and beta values ?!
2 VTX 6950 2Gb
1 Gigabyte 6950 2Gb
Also A Pitcairn GPU but didn't try yet.
2 os on W8.1 64
1 os on W10 x64
No card mine, and don't have error. I've never seen any hash start

I post my config perhaps and i did it something wrong ?!
My start cmd file
ce_cn_gpu_miner64.exe --no-cpu -c config.txt -o pool.supportxmr.com:5555 -u 44kXLYVXRE############PDcW4kQx+5000 -p 6950_JCE
pause
Log File
Analyzing Processor topology...
AMD Athlon(tm) Processor 1640B
Assembly codename: athlon64
SSE2 : Yes
SSE3 : Yes
SSE4 : No
AES : No
AVX : No
AVX2 : No
Found CPU 0, with:
L1 Cache: 64 KB
L2 Cache: 512 KB
Detecting OpenCL-capable GPUs...
Found GPU 0, with:
Vendor: AMD
Processor: Cayman
Device: 02:00
Compute-Units: 22
Cache Memory: 0 KB
Local Memory: 32 KB
Global Memory: 2048 MB
Addressing: 32-bits
Preparing 1 Mining Threads...
+-- Thread 0 config ------------------------+
| Run on GPU: 0 |
| Multi-hash: 864 |
| Worksize: 32 |
| Factor Alpha 64 |
| Factor Beta 8 |
+-------------------------------------------+
Cryptonight Variation: Cryptonight V8 fork of Oct-2018
Starting GPU Thread 0, on GPU 0
Created OpenCL Context for GPU 0 at 000001c29b8c6660
Created OpenCL Thread 0 Command-Queue for GPU 0 at 000001c29d012f80
Scratchpad Allocation success for OpenCL Thread 0
Allocating big 1728MB scratchpad for OpenCL Thread 0...
Compiling kernels of OpenCL Thread 0...
Kernels of OpenCL Thread 0 compiled.
09:02:21 | Monero (XMR/XMV) Mining session starts!
09:02:21 | GPU Compute allocation starts at 80% and reaches 100% after ~5min,
09:02:21 | during this time, the hashrate may be unstable and inconsistent.
09:02:21 | Let the miner warm-up if you're tuning for performance.
09:02:22 | Connecting to mining pool pool.supportxmr.com:5555 ...
09:02:22 | Connected to pool. Now logging in...
09:02:22 | Successfuly logged as 44kXLYVEmkUXRECm8eza1PF###############EJ9cePDcW4kQx+5000
09:02:22 | Pool changes Difficulty to 5000.
09:02:23 | Pool sends a new Job.
09:02:53 | Hashrate GPU Thread 0: 0.00 h/s - Total GPU 0: 0.00 h/s
09:02:53 | Total: 0.00 h/s - Max: 0.00 h/s
09:03:02 | GPU 0: Temp: 37C - Fan: 24% -- Shares: Good: 0 Bad: 0
09:03:45 | Pool sends a new Job.
09:04:49 | Pool sends a new Job.
09:05:59 | Pool sends a new Job.
09:06:14 | Stop signal received, Quitting...