3.6 KiB
3.6 KiB
4x Radeon AI PRO R9700 — Rackmount LLM Server Build Plan
Goal: Local LLM inference/training rig running 3-4x AMD Radeon AI PRO R9700 (32GB) GPUs, rack-mounted in a full-size 19" rack.
GPU
| Spec | Value |
|---|---|
| Model | AMD Radeon AI PRO R9700 32GB |
| VRAM | 32GB GDDR6, 256-bit bus |
| Interface | PCIe 5.0 x16 (backward-compatible with PCIe 4.0 slots at x16 bandwidth) |
| Form factor | Dual-slot, blower-style cooler |
| TDP | 300W |
| Quantity | 4x → ~1,200W GPU load alone |
Blower coolers exhaust heat out the back of the case rather than into it — important for stacking 4 cards close together.
Motherboard
Gigabyte MZ32-AR0 (Rev 1.0)
| Spec | Value |
|---|---|
| Socket | Single SP3, EPYC 7002/7001 series |
| Form factor | E-ATX (305mm x 330mm) |
| PCIe slots | 4x full PCIe Gen4 x16 (Slot_3, Slot_4, Slot_6, Slot_7) + additional Gen4 x8 / Gen3 slots |
| Memory | 8-channel DDR4 RDIMM/LRDIMM, 16 DIMM slots |
| Management | ASPEED AST2500 BMC (IPMI) |
Note: CPU/memory socket sits close to the PCIe slots — plan for PCIe riser cables to give the R9700's clearance and to route to rear chassis slot cutouts.
CPU
AMD EPYC 7282 (Rome / 2nd Gen, SP3)
- 16 cores — sufficient since the workload is GPU-bound, not CPU-bound
- Full access to Rome's 128 PCIe lanes on this single-socket board
- Budget-friendly used-market option vs. Threadripper PRO
Memory
- Type: DDR4 RDIMM or LRDIMM only — unbuffered (UDIMM) will not POST on SP3
- Size to your model/dataset needs; 8-channel config gives strong bandwidth for CPU-side preprocessing and system overhead
Power Supply
- Estimated system draw: ~1,200W (GPUs) + CPU + overhead → 1,600-2,000W PSU needed
- At 4U rack size, use a redundant CRPS-style server PSU rather than a single consumer ATX unit — better suited to 24/7 operation
Chassis
4U rackmount, E-ATX compatible, full-depth (420mm+)
Candidates:
- Rosewill RSV-L4620-class (supports up to 4 GPUs, E-ATX compatible, hot-swap bays)
- Rackchoice/RackOwl 4U E-ATX (7 full-height expansion slots, 420mm depth)
Requirements:
- Front-to-back airflow (matches R9700 blower exhaust direction)
- 7 full-height PCIe slot cutouts at rear
- Riser card support if GPU clearance near CPU socket is tight
Rack
42U full-size rack, 19" width, ≥1,000-1,100mm usable depth
| Item | Space |
|---|---|
| GPU server (4U chassis) | 4U |
| UPS | ~2-3U |
| Network switch | 1U |
| Cable management / PDU | 1-2U |
| Used now | ~8-10U |
| Free for expansion | ~32-34U |
- Choose an enclosed rack (side panels + front/rear doors) for dust control and directed airflow, appropriate for a dedicated server room/garage.
- Confirm listed depth explicitly supports full GPU servers — many "42U" racks are sized for shallow network gear, not 420mm+ deep GPU chassis.
Sourcing links
- Netzwerkschrank, 37HE 600x1000 — candidate rack; maybe go taller than 37HE
- Gigabyte MZ32-AR0 Rev1.0 + EPYC 7282 16-Kern 2.8GHz — mainboard+CPU bundle matching the spec above. Still needs RAM — prefer older/used DDR4 RDIMM over new, it's cheaper.
Open Items / Next Steps
- Verify current ROCm/Linux driver compatibility for R9700 on Rome-era (SP3) PCIe topology
- Confirm riser cable part numbers/compatibility with MZ32-AR0 + chosen 4U chassis
- Size UPS capacity against full system load (GPU server + switch + growth headroom)
- Source EPYC 7282 + MZ32-AR0 (used/refurb market)
- Confirm chassis rail kit compatibility with target rack