I suspected that the FPS dips could be caused by some Nvidia driver issue, so I tried disabling Nvidia-specific features such as DLSS and DLAA (I tried switching between them as well to no avail). The FPS dips are not caused by the graphics settings being set too high, as I tested it...
Noise level: HDDs iddle/ fans 50%=32 dB, fans 100%= 39dB (need to change the 14mm rear exhaust fan) Main usage: download station and PLEX. Things to improve : another stick of 8gb ddr3, a pci-e sata controller, 2 6TB hdd, 2 512gb SSDs for SSD Caching, 2x92 Noctua case fans...