The verdict

CPU
GMKtec K8 Plus has 7.1x the CPU throughput (28,362 vs 4,000 PassMark).
Plex
GMKtec K8 Plus transcodes more 4K HDR streams (~5 vs ~4).
RAM ceiling
GMKtec K8 Plus takes more RAM (96GB vs 16GB).
Local AI
QNAP TS-464 has a PCIe slot for a low-profile GPU - the other needs a DIY build for local LLMs.

Which wins for each job

Job GMKtec K8 Plus QNAP TS-464
Plex / Jellyfin ~5 streams win ~4 streams
Frigate NVR add a detector ~4 cameras win
Proxmox / VMs 28,362 PassMark win 4,000 PassMark
Firewall / router 2 NICs 2 NICs
Local AI / LLM no slot PCIe GPU slot win

Approximate - capacity estimates from curated specs, the same logic as the recommender. Verify against your exact setup. Prices move; check the retailer.

Full specs

Spec GMKtec K8 Plus QNAP TS-464
Price (list) $520 $549
CPU AMD Ryzen 7 8845HS Intel Celeron N5095
Cores / threads 8 4
PassMark 28,362 4,000
iGPU Radeon 780M (RDNA3) Intel UHD (16 EU)
NICs 2 2
NIC model Intel I226-V Intel I225-V
RAM max (GB) 96 16
M.2 free 1 2
PCIe slot none x4
Idle (W) 14 14
TDP (W) 54 15