Custom PC Building

I have 2 questions that may or may not be related:

1. My gaming PC periodically has full system crashes while I'm playing some games. I've tried looking at crash reports but I couldn't really figure out what was different from looking at them. I've seen it suggested that it could be overheating, although it's kind of hard to tell since the temp range when I check isn't that high, but I do feel a lot of heat coming off the machine when I stick my hand over the vent and I hear the fans working hard when I'm playing some games.

2. I was thinking that it might be worth it to try to upgrade some parts to maybe alleviate one possible source of issues. So what I'm wondering is what the best approach would be. For example would getting a better graphics card make it work less hard and produce less heat? Or does a more powerful card just produce more heat? How much can I reasonable upgrade cooling systems given a fixed amount of space in the case? It's been a while since I've manually swapped out parts. Last 2 PC I opted for just buying pre-made although in the past I built one. The one I have now is an Alienware Aurora R11 from a few years ago and it's got an RTX 2070 Super for a graphics card. Does it make sense to try to upgrade it? If so, is it worth going for the newest series or would it be fine/better for my purposes to go to the 30 series?