High thread concurrency would do it.
Delete *.bin files and try something low like:
-w 256 --thread-concurrency 4096 -I 12
That's my basic desktop usage 7850 settings, 7870 would handle it fine if the card is working fine.
7870's have 1280 shaders as well, but you already tried without that flag.
I have 2 x 7870XT Joker cards
My command line:
cgminer.exe --scrypt -o xxx:3333 -u user.1 -p x -o xxx:3333 -u user.1 -p x -I 12 -g 2 -w 256
getting 450 kh/s per card, total 900 kh/s. You could push them to 1000 Kh/s but they get too hot in my case.
I am doing the finetuning with MSI Afterburner
tried both, nothing changend - cgminer still crashes with scrypt (bitcoin is still working)
Apart from the slightly high value on thread concurrency and the fact that 7870xt doesn't have 2048 shaders, I can't see anything wrong with those settings. Did it connect to the pool? Is the OpenCL box checked in GPU-z?
yepp, got that but changend nothing - also checked is, openCL is available
Looks like I have a big driver problem - in case of mining other coins I would set up a new system, looks like that the settings are not the problem
crash details:
name: APPCRASH
appname = cgminer.exe
fail-modulname = amdocl.dll