Help! My Gaming Performance Took a Nosedive After Moving My PC

Hey everyone, I'm really struggling with my PC's performance after moving it. Just a week ago, everything was running smoothly. I was playing games like Elden Ring and Oblivion without any hiccups. I transported my PC to my family's house to house-sit for the weekend and did some much-needed cleaning with compressed air while I was there. No issues while gaming at their place.

But since bringing it back home, things have gone downhill. Elden Ring is lagging like crazy, and Oblivion won't even load my saves—it just crashes. Sometimes, after shutting down, the fans keep running even though the monitors turn off. Regular PC tasks seem fine, but games are acting weird. The weirdest part? Sometimes the games perform okay, and then the problems come back when I boot up again. My monitors are connected to the GPU, and I don't have integrated graphics. My GPU usage is below 50% while gaming, and I suspect a bottleneck could be an issue, but these games used to run great. Temperatures seem normal, so I'm not worried about overheating.

I'm beginning to think something might have happened while I was moving it, but I can't find anything wrong. Here are my specs:

- Windows 10
- AMD Ryzen 3600
- NVIDIA EVGA 2070 Super
- ASUS Prime X570-P
- 32GB DDR4 RAM
- 1TB NVME SSD & 2TB NVME SSD

Here's what I've tried so far:
- Reseated the GPU power cables and the GPU itself
- Reseated the RAM (I had a brief scare where it failed to POST, but I think I just slotted them incorrectly)
- Updated/reinstalled graphics drivers (haven't used DDU yet)
- Ran a memory test which came back clean
- Updated CPU drivers
- GPU Heaven Benchmark runs perfectly at 99% GPU usage
- Did a quick virus scan, and I'm planning to do a full scan soon.

Anyone have ideas on what could be going wrong?