There is no 'max temperature' besides a physical limit in which silicon melts, you can look that up, around 120C+, not like you could possibly get that hot. As for when does errors occur in software results, the higher your clock frequency, the lower the temperature threshold is for creating errors, but this is not an absolute constant, the temperature at which errors are induced are unique to your own graphics card. The reason why heat causes errors in high frequencies is because heat is a form of radiation noise, and noise makes it hard for 111000111 to be heard as 111000111 and not, say, 111010111.

Only issues are with HHC GPU only. Am not crunching any other project at this time.

Currently using a Corsair 850 Gold rated PSU. Since it does work fine with milkyway, pretty sure its how WCG coded the application. Haven't run milkyway in a few months, just unticked HCC to switch over once my cache of HCC dries up just to check again. But since reinstalling CCC, everything seems to be back to normal except the lag. One interesting note is I read a comment somewhere here on these forums that since my card is double precision that its possible its not running at full speed. Have no clue at this time as to why and to many folks guessing quick fixes so will just let it go. Hopefully, WCG can refine the code in future projects. Am currently looking for a 7950 as it seems the 7000 series don't have many issues. Thanks for the response.

Another note. Have read in another thread that folks are seeing better results shutting off hyperthreading. Just lowered from 22 threads and do see less lag. The lower I go, the less lag but still some at 18 threads. Might try removing hyperthreading just to see if it does work better.
Note 2. Played around with the hyperthreading and turbo by shutting them off. A little better but not worth leaving these off. Back on.
Note 3. Changed out to HDMI from display port. A noticable difference but still some lag.
Since playing with the settings and trying different options, back to the driver kicking out. Have uninstalled and reinstalled different CCC packages but still screwed up. Have it all uninstalled now and running file check in hopes it finds any corruption. My 5670 on the other cruncher is doing fine. Wondering if double precision cards don't like HHC GPU seeing others with double precision are having issues vs 7700 and 7800 (single precision) don't seem to have issues from what I have read so far.