I believe the setx GPU_MAX_ALLOC_PERCENT 90 command pertains more to how much maximum memory on the GPU can be allocated for process to use. Likewise the GPU_SINGLE_ALLOC_PERCENT command sets the amount of memory a single process can utilize. Both of these settings deal with the allocation of memory and not the core utilization. To adjust that you would need to change settings within cgminer itself if available.
Since mining programs are meant to utilize the GPU as much as possible to deliver maximum hashrates you may be better off trying to improve airflow so your cards will naturally cool down. Are your cards in an enclosed case? if so you may need to add more case fans, or alternatively you can simply remove the side panel for more airflow to see if it helps. If they are in an open-air frame you may need an external fan blowing ower it to help cool it down more.
Thank you mate! So I'm just wasting time trying to limit GPU load by changing batch file.
Yes, I use nornal PC case so it's closed. I do have one intake fan and one for outflow. But these seem not enough for mining at 99% load.
I will now open the case and see if that makes any difference. If it won't I will simply need to decide to quit mining on PC and buy mining rig or Antminer.