i would say the Cmos part you ordered isn’t the same Cmos battery Number as the old one taken out, some are different but look the same, some are 3, 5 and 9 volts. seesm like your underpowered to run Cmos when engaged in a game, could also be the game your playing is too high for your graphics card as well.
anyway, the dell has this issue alot, take a look here at this video and follow the steps, see if that troubleshoots the issue for you, https://www.youtube.com/watch?v=Og8EzbhXgWI&vl=en