Crap. Now try underclocking your memory to 300 MHz, maybe that helps...

Did you try leaving it alone(logoff or unplugmonitor or..) and calculate from "2^32 * share/s = hash/s" from your pool site(~3hours to get most accurate). I know there's some variance, but should clearly see if they are still running 50% or 99%.

Do you have the crossfire bridges connected?  If so, disconnect.

Have you disabled CF with aticonfig?  If not, aticonfig --crossfire=off

Do you have enough power on your PSU for the three cards?  You probably need at minimum a 750W or so to handle that, preferably with a single rail or you'll overload the rails.  I've seen GPU's throttle if they aren't getting enough power.

Hi All,

I tried yesterday to setup a mining rig with 2 x 5850, using ubuntu 11.04, got this weird issue. when I use only 1 gpu, I get 100% utilization, but when I try to use 2, each only runs at 50%.

I think "--device" starts in 1, but you put 0, and then you got an error.

I finally got it working on a clean 10.10 install with Catalyst 11.04 and SDK 2.1 and poclbm
I kept getting this segmentation fault afther the catalyst install on 11.04, 10.10 and 10.04, then i thought i must be the hardware so i changed the monitor, but the same segmentation fault kept showing up again on 10.04 10.10 and 11.04 even gave a error ./default policy.sh does not support version. Oke they were nameless monitor brands that someone gave to me, but that shouldn't matter. Finally i switched to the monitor of my main computer and YES, this time no segmentation fault. i have used the install procedure from all around the forum and beyond and it went smoothly first time install, from catalyst to SDK/OpenCL up to poclbm.

Edit:
Working version on 64 bits Ubuntu 11.04 - Ati Catalyst 11.4 - Ati SDK 2.3 with poclbm and phoenix miner in 31 steps:
Hardware:(budget mining)MSI 770-c45 Mobo with athlon2 X2 cpu - cooler master 650w powersupply - 1x GPU Ati 58xx

1. sudo apt-get install build-essential cdbs fakeroot dh-make debhelper debconf libstdc++6 dkms libqtgui4 wget execstack libelfg0 g++ libboost-all-dev subversion git-core python-numpy
2. sudo apt-get install ia32-libs
3. cd ~/; mkdir catalyst11.4; cd catalyst11.4/
4. wget http://www2.ati.com/drivers/linux/ati-driver-installer-11-4-x86.x86_64.run
5. chmod +x ati-driver-installer-11-4-x86.x86_64.run
6. sudo apt-get remove --purge xserver-xorg-video-radeon
7. sh ati-driver-installer-11-4-x86.x86_64.run --buildpkg Ubuntu/natty
8. sudo dpkg -i fglrx*.deb
9. sudo aticonfig --initial -f
10. sudo aticonfig --input=/etc/X11/xorg.conf --tls=1
10a.reboot
11. wget http://download2-developer.amd.com/amd/Stream20GA/ati-stream-sdk-v2.3-lnx64.tgz
12. wget http://download2-developer.amd.com/amd/Stream20GA/icd-registration.tgz
13. sudo tar xvfz ati-stream-sdk-v2.3-lnx64.tgz -C /opt
14. sudo tar xvfz icd-registration.tgz -C /
15. echo export DISPLAY=:0 >> .bashrc
16. echo export LD_LIBRARY_PATH=/opt/ati-stream-sdk-v2.3-lnx64/lib/x86_64/:$LD_LIBRARY_PATH >> .bashrc
17. source .bashrc
18. wget http://pypi.python.org/packages/source/p/pyopencl/pyopencl-0.92.tar.gz
19. svn checkout http://svn.json-rpc.org/trunk/python-jsonrpc
20. svn checkout http://svn3.xp-dev.com/svn/phoenix-miner/trunk
21. git clone git://github.com/m0mchil/poclbm poclbm
22. mv trunk phoenix
23. tar zxfv pyopencl-0.92.tar.gz
24. cd pyopencl-0.92
25. ./configure.py --cl-inc-dir=/opt/ati-stream-sdk-v2.3-lnx64/include/ --cl-lib-dir=/opt/ati-stream-sdk-v2.3-lnx64/lib/x86_64
26. make -j3
27. sudo make install
28. cd ../python-jsonrpc
29. sudo python setup.py install
30. cd ~
31. chmod +x phoenix/phoenix.py poclbm/poclbm.py