computer turning off during playing

I think that the imbalance is due to the high cpu temperature.

While the cpu temperature is high, your pc turns to run in low performance and turns off.

First of all, welcome to the forums.

Now I'm not a tech expert, but it would really help if you post your pc specs. Is it enough to run PvZ: GW? Are the components in good condition? I'm guessing your PSU has a defect, but again, I'm not sure unless you post your specs. It could also be a problem with your CPU or graphics card.

Sounds like an overheating problem. My guess is your CPU or video card are getting too hot, which would cause your system to shut itself off to save those components from being destroyed. If you can't afford a better case, try opening it and pointing a fan in there.