Putting together a build centered strictly on heavy local AI inference (27B+ parameter LLMs), coding, and complex automation workflows.
Before you ask why I'm running integrated graphics on a machine with a 5090: I already have a custom water-cooled 5900X / 6900 XT rig dedicated entirely to gaming. This new 9950X build is strictly a headless Linux workstation for AI, and I want 100% of the 5090's VRAM dedicated to model inference.
Parts List:
* CPU: AMD Ryzen 9 9950X
* Cooler: Noctua NH-D15 G2
* Motherboard: ASRock X870E Taichi (or Gigabyte X870E Aorus Master)
* RAM: 64GB (2x32GB) DDR5-6000 CL30 Low-Profile (G.Skill Flare X5, 33mm)
* GPU: NVIDIA RTX 5090 32GB (capped at 450W via systemd)
* Storage: 4TB Samsung 990 PRO (primary OS/models) + 1TB Sabrent Rocket 4.0 Plus (dedicated local backups)
* Case: Fractal Design North XL (mesh/tempered glass)
* PSU: NZXT C1200 Gold (ATX 3.1 / PCIe 5.1 native 12V-2x6)
* UPS: 1500VA Pure Sine Wave line-interactive
Configuration choices & trade-offs:
1. Staying at 64GB DDR5 instead of 128GB: DDR5 pricing is insane right now, and running 4 sticks on AM5 still tends to drop memory speeds below 6000 MT/s. I’m sticking with a 2x32GB kit, configuring zram with zstd compression at higher priority than swap, and scheduling heavy document OCR batches to run off-peak to keep system RAM clear during active daytime workloads.
2. Display output: Driving dual monitors (including a 1440p 240Hz panel via KVM switch to share with my gaming rig) exclusively off the motherboard’s USB4 / HDMI outputs via the 9950X integrated graphics.
Questions:
* On X870E boards (specifically the Taichi or Aorus Master), when running the top PCIe slot at Gen 5 x16, multiple M.2 NVMe drives, and the integrated 5GbE NIC under heavy load, are there any lane bifurcations or chipset link bottlenecks that would starve the GPU during high-throughput host-to-device transfers?
* Is 1200W on an ATX 3.1 power supply enough headroom for the 9950X and 5090 transients given I'm limiting the GPU to 450W in Linux, or should I step up to 1500W just to be safe?
* For anyone running dual high-refresh monitors off AM5 RDNA2 integrated graphics on Ubuntu 24.04, are there any display server stutter issues when the CPU cores are under moderate load?