I've had the same problem with 3 different soundcards. Crackling and eventual hard reboot only occurs with RAM set at 3800/1900IF and 3733/1866IF. When I set RAM to 3600/1800IF the crackling goes away. I tried many different SOC & VDDG voltages. Strangely the RAM will pass ram test for hours without issue.
For the time being I have left it at 3600/1800IF because at 4K gaming the difference was frankly margin of error.
Focus on lowering the timings, if you can get it to 3600 CL14 with 1800IF, the gaming performance will be just as good as you had with 3800, if not better