I'm curious, what are the unmodified values for GPU_FORCE_64BIT_PTR, GPU_MAX_HEAP_SIZE, GPU_USE_SYNC_OBJECTS, GPU_MAX_ALLOC_PERCENT, GPU_SINGLE_ALLOC_PERCENT or is there a way to reset them to values before setx command? I ask this because I'm currently mining with my daily pc that i play games etc. Would any of these commands affect gaming etc. negatively?
I guess they are documented in the AMD SDK and by default they are not defined. Unless you know defaults may be better to remove those variables from the global environment (see advanced system properties, I believe, they can be found and deleted there if were set at least once).
I can't say about affecting games, but for few known to me systems setting GPU_FORCE_64BIT_PTR=0 resulted in Calymore's ETH dual miner crash with RX470 cards. So I used all them but removed after that. On some other systems setting this showed me 3GB of VRAM for 380X and RX470 card instead of real 4GB.
So in short, yes, I would remove all of them and use in the form of set (not setx) only those that really affect mining performance (by testing on a particular system).