Intensity Issue [CGminer, litecoin BAMT, 7950, Scrypt]

[minefish]

Hi guys,

I seem to have run in to an issue which I can't solve alone.

Hardware:

- 4 x Sapphire HD 7950 3L
- Gigabyte GA-990FXA-UD3
- Lepa G1600 PSU
- 4GB ram
- 2 x non-powered risers

Software:

- Litecoin BAMT http://forum.litecoin.net/index.php/topic,2924
- 13.4 AMD Drivers
- CGminer 3.1.0



Situation 1:

cgminer.conf

"intensity" : "17,20,20,20",
"vectors" : "1,1,1,1",
"worksize" : "256,256,256,256",
"kernel" : "scrypt,scrypt,scrypt,scrypt",
"lookup-gap" : "0,0,0,0",
"thread-concurrency" : "20480,20480,20480,20480",
"shaders" : "1792,1792,1792,1792",
"api-port" : "4028",
"expiry" : "1",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1,1,1,1",
"gpu-engine" : "1115,1115,1115,1115",
"gpu-memclock" : "1500,1500,1500,1500",
"gpu-powertune" : "20,20,20,20",
"auto-fan" : true,
"temp-cutoff" : "95,95,95,95",
"temp-overheat" : "85,85,85,85",
"temp-target" : "75,75,75,75",
"log" : "5",
"no-pool-disable" : true,
"queue" : "0",
"scan-time" : "1",
"scrypt" : true,
"shares" : "0",
"kernel-path" : "/usr/local/bin"

Hashing Speed:

GPU0: ~ 600
GPU1: ~ 660
GPU2: ~ 660
GPU3: ~ 660




Situation 2:

cgminer.conf

"intensity" : "20,20,20,20",
"vectors" : "1,1,1,1",
"worksize" : "256,256,256,256",
"kernel" : "scrypt,scrypt,scrypt,scrypt",
"lookup-gap" : "0,0,0,0",
"thread-concurrency" : "20480,20480,20480,20480",
"shaders" : "1792,1792,1792,1792",
"api-port" : "4028",
"expiry" : "1",
"gpu-dyninterval" : "7",
"gpu-platform" : "0",
"gpu-threads" : "1,1,1,1",
"gpu-engine" : "1115,1115,1115,1115",
"gpu-memclock" : "1500,1500,1500,1500",
"gpu-powertune" : "20,20,20,20",
"auto-fan" : true,
"temp-cutoff" : "95,95,95,95",
"temp-overheat" : "85,85,85,85",
"temp-target" : "75,75,75,75",
"log" : "5",
"no-pool-disable" : true,
"queue" : "0",
"scan-time" : "1",
"scrypt" : true,
"shares" : "0",
"kernel-path" : "/usr/local/bin"

Hashing Speed:

GPU0: ~630
GPU1: ~630
GPU2: ~630
GPU3: ~630

Issue:

When I lower the intesity to 17 on GPU0, my other cards run at their normal speed.
But whenever I tune the intensity up to 20 on GPU0 the other cards start to hash way below their normal speed.

Extra information:

- Before this I had a 7850 sitting in the same slot as a GPU0, I encountered the same problem.
- I do not have this issue when I use windows 7.


Kind regards,
Nick

[8kmode]

edit - re-read.
perhaps its the GPU?
Don't the 7950's need 500w PSU min each?

[minefish]

edit - re-read.
perhaps its the GPU?
Don't the 7950's need 500w PSU min each?

No, it is not the GPU and the PSU is more then enough.

Maybe it has something to do with GPU0 being the primary adapter?