Freezing Sims 4 Issue

@hotpink4956  Sorry for the late-ish reply.  Which computer froze: the one with your CPU and board and your fiancé's other components, or the one with your fiancé's CPU and board and your other components?  If it's the first, then this probably is your CPU, although it could be the board too.  For the board itself, look for bulging capacitors, which would be an obvious sign of trouble.

Otherwise, you may need to find a computer shop that has a compatible processor and mainboard for testing: they'd drop your CPU into their board, or drop one of their processors into yours.  Since your hardware is six years old, it's harder to find these days, although a local repair store should have something suitable on hand.  And you wouldn't want to buy a replacement part without knowing for sure which component was defective.

I'm sorry I don't have something better to offer, but both processors and motherboards are difficult to repair, if it's even possible, and perhaps not worth the investment.  If the board turns out to be the issue, you might be able to find a replacement for a reasonable price and get a few more good years out of this system.  If it's the CPU, a new 4790K would be almost $300, although they're cheaper used on Ebay.

Regardless, the first step is to find someone who can test each component separately and confirm which one is causing the crashes.