Why Am I Getting Low FPS with a High-End PC?

Hey everyone, I'm having some frustrating issues with low FPS in various games, despite having a high-end setup that should be performing better. Here are my specs: - Intel i9-10900K - NVIDIA RTX 4080 - 64GB DDR4 RAM at 3887 MHz (I had to manually tune it since XMP doesn't work; it's rated for 4400 MHz) - MSI Z590 Gaming Force motherboard (it's used and has some issues like non-functional SATA ports) - 2 NVMe SSDs (one for Windows and one for games) - 2x 32" monitors (240Hz, one set to 60Hz in vertical mode) Here's how it's performing: - No Man's Sky: ~100 FPS on planets, ~150 FPS in space with DLSS - Warframe: 100-120 FPS (I used to hit 250-300 FPS with an RTX 2060) - Minecraft (1.18/1.19): ~100-120 FPS, no shaders used - Valorant and CS:GO perform as expected with full FPS Even though I suspect a 10-15% CPU bottleneck, this doesn't seem right for an RTX 4080. The GPU usage rarely hits 100%, and temperatures are good. Things I've done: - Just did a fresh Windows install about a week ago. - Cleaned and reinstalled NVIDIA drivers. - Tweaked various settings in Windows (like disabling certain services and enabling game mode). - Set power settings to max performance. - I think my BIOS might be outdated since the motherboard is a bit sketchy to flash. Any ideas on what I could do? Happy to share logs or benchmarks. It really feels like my GPU isn't being utilized to its full potential, and I'm not getting the performance I expect.