I found a workaround to my problem. It should work for you as well. It's a bit of a hack, but it works.
Here's what I did:
download AOCLBF: http://forum.bitcoin.org/index.php?topic=10264.0
keep a downloaded copy around somewhere.
Install it as instructed (basically place the 3 files into your guiminer filder location).
You DON'T have to use this miner for mining, but it will allow you to OC and set fans
The very first time you run it, it will ask you how many miners to create. I specify the number of GPUs, not the cards, so for the 2 6990 + 6850, I tell it to create 5.
You will see "client tabs" (ignore these for the moment) and a tab for each GPU. Here I use the GPU-related tabs to set my clocks and fans. I answer "no" to setting on next startup.
After I OC the way I want, I simply start my usual miners. I do not use the AOCLBF for mining (at least not yet).
Here comes the tricky part. On next restart/reset, this program most likely will not detect your GPUs correctly. This is probably why MSI Afterburner, trixc and others don't work either.
What I do at this point is delete all the files related to AOCLBF (this includes a clocks.xxx file) and reboot.
After reboot I repeat the install process and keep going.
I hope this solves your issue Mike.
If this helps, feel free to send me that bounty, but I won't cry if you don't: 15KwcqgcxjsXx6XGJgv56Ps6AjbeQP3Ge5