Hey I have an HD6870 and am mining vertcoin (so the kh is half of other coins I believe)

So far, I can get 100kh with the following settings:

vertminer.exe --scrypt-vert -o stratum+tcp://xxxxxxxx -u xxxx.xxxxx -p x --thread-concurrency 4480 -I 13

If I turn up my intensity, I can get it up to about 140 but the GPU gets way too hot (like 80-85 degrees)

Others have suggested that I play around with the thread concurrency in multiples of 64 but if I put anything other than 4480 in, my speed drops to 18kh

I tried it at the following tc levels and every one of them drops the speed top about 18kh:
5760, 6400, 8192 ,6720

Also, sometimes I notice after I close and start up the miner later that even my 4480 (that I get 100kh) with will drop to 15-18 until I restart my computer.  Unfortunately, trying these other thread-concurrencys after a fresh restart doesn't do anything to raise the kh

I am confused why this happens to even my good settings and if its related to my issue of other tcs never getting over 20kh.

Any advice on this or how I can get it more up to the 125-130 range while keeping my GPU temp down would be greatly appreciated.

Thank you