I've looked everywhere for an answer to this, but everywhere it just states it's the solution, not the problem. But for me it definitely is. Here are my specs:
AMD Ryzen 7 7700X 8-Core Processor
32 gb ra
AMD Radeon RX 6700 XT

The game runs butter smooth with or without the FPS Limiter, but my GPU runs less hard with one obviously. Problem is, when I use one, keeping to 30fps when idle with a high of 60 (or at any rate that's not just letting it run crazy with fps) it causes a soft crash after about 20 min- to an hour; effects running but game is unresponsive forcing me to end task. I follow the fps and it crashes even when it's just sitting at 30. I have narrowed it down to that issue with two different fps limiters, game runs fine but the gpu has to chug without one. I'd like to be able to use one and can't understand why an fps limit would be CAUSING the crashing... but it is. What could be causing it? Could it be two things together which are incompatible? I'd appreciate the help. Sims 3 is a poorly optimized and programmed mess... but it's my true love.

I would check what your screen refresh rate is, and match your vsynch/ freesynch/ FPS limit to that.