Who wants to jump in, Thats fucked
I suspect you already gave the reason: "Loving this miner Because it compiled a SDK2.5 .bin, Making itself run off SDK 2.5 Whilst i have 2.6 installed"
This.
It is the craptastic beyond all belief SDK 2.6 (worst release by AMD yet).
DONT USE 2.6 DONT USE 2.6 DONT USE 2.6 DONT USE 2.6 DONT USE 2.6 (<- maybe that should be my signature)
You may say "why does the old cgminer not have an issue"? cgminer "caches" kernel binary data as .bin files. So since they were already created the old version won't create new ones and use the fucked to all hell SDK 2.6
An experiment.
1) Look in old cgminer dir. You should see some files with .bin extension. Copy them somewhere safe.
2) Now delete the copy in old cgminer dir. launch cgminer - likely you have the same poor performance.
3) Look in old cgminer dir. You will notice it recreated the .bin files. These are the crappy ones (built w/ sdk 2.6). Delete them
4) Copy your safe copy (step #1) of the .bin files back to old cgminer. launch it. you should have good performance again
5) Now delete the .bin files in NEW VERSION of cgminer dir. Copy the "old" .bin files from your safe directory (step #1).
6) Launch new cgminer. You should have same performance as the old cgminer.
Please post your results as it will confirm P4man hypothesis.