Listen guys, I have checked this and new drivers ARE A TRUE POISON. At least when Groestlcoin is in question THE SPEED OF HASHING IS ALMOST DUPLICATED!

On R9 280x my previous hash rate was 6.8 MH/s. Now it's 11.43 MH/s.

Fans on the card are not cranking - but rather wheezing with a very high pitch and started to radiate a serious heat. Who says Groestl is friendly to the cards...

How to achieve this result:

1. Get yourself BAMT 1.6.0 (or any other 32-bit Linux distro will do):

http://www.reddit.com/r/BAMT/comments/207rdz/release_bamt_v160_scrypt_scryptn_darkcoin/

2. Get yourself a decent sgminer-sph, I am using this one:

https://github.com/badman74/sph-sgminer

3. Get yourself the latest AMD 14.6 drivers, files are the follows:
linux-amd-catalyst-14.6-beta-v1.0-may23.zip
AMD-APP-SDK-v2.9-lnx32.tgz
ADL_SDK.zip

4. Now, uninstall old drivers, reinstall new drivers, RECOMPILE THE SGMINER:

The EXACT procedure is noted here:
http://rumorscity.com/2013/12/08/amd-display-driver-update-for-r9-290x-on-bamt-litecoin-miner/

NOTE:  Please follow the procedure EXACTLY.

5. DELETE the old compiled CL file, which is usually hidden here:
/opt/miners/sgminer-4.1.0-sph

NOTE: The key to enhanced performance is hidden in NEW on-the-fly re-compilation of .cl files.

6. Everything else is as usual. Mine cards speeds up to 11.43 MH/s:

http://www.kapion.si/Mining-gro.jpg

7. Parameters I am using:
  core_speed_0: 300
  core_speed_1: 1140
  core_speed_2: 1140
  mem_speed_0: 300
  mem_speed_1: 1000
  mem_speed_2: 1000
  core_voltage_0: 1.131
  core_voltage_1: 1.131
  core_voltage_2: 1.131

8. Config file I am using (partial print):
    "auto-fan" : true,
    "gpu-fan": "30-99",
    "temp-cutoff" : "95",
    "temp-overheat" : "85",
    "temp-target" : "79",
    "worksize": "256",
    "intensity" : "20",
    "gpu-threads" : "1",
    "thread-concurrency" : "8192",
    "lookup-gap" : "2",
    "vectors" : "1",
    "shaders" : "2048",
    "api-port": "4028",
    "api-listen": true,
    "api-allow": "W:127.0.0.1",
    "failover-only" : true,
    "no-pool-disable": true,
    "no-submit-stale" : true,
    "queue": "0",
    "log" : "5",
    "gpu-powertune" : "20",
    "algorithm" : "groestlcoin",
    "kernel-path": "/usr/local/bin"