Your intensity is too high, you need to lower it if you want to use your PC while mining. Which miner are you using? Post your commandline arguments and we'll figure it out.
I use Pheonixminer, and I have tried -mt 2 -rvram 8000 to reserve some vram. I also tried -vmr 50 to use only 50% of the vram, but neither worked.Just tried out using -mi commandline to change the intensity to 8, default was 12, the problem does seem getting much better now, I will try 7 or 6, and it does seem to affect hashrate a lot either. Thanks!!