Re: CGMINER GPU FPGA overclock monitor fanspeed GCN RPC linux/windows/osx 2.3.1

...
You answered it good enough. I can just use the older version. I would probably lose more then I would gain messing with my rig drivers.

Actually, the most likely cause is the fact that you have already messed with them.
(whether you realise it or not)

I renamed the original cgminer as a backup, and did a fresh install of the new version with a copy of the config file. I then realized the hashrate was wrong, deleted the new copy and renamed the original and its working fine again. What could have been messed up?

I meant that red bit I just highlighted

If it's windows then any ATI dirver update will have messed it up if it changed the SDK (and other changes can also)
If it's linux and you did an upgrade ... same thing.

The 'current' SDK determines what is in any new *.bin files you generate.
When you switch back to an old version of cgminer you are using the old *.bin generated with an old SDK unless you delete them.