# 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.

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## 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.

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## 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.

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## 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

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## 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

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## 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

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## 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

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## 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.

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## Sourcing links

- [Netzwerkschrank, 37HE 600x1000](https://www.ebay.de/itm/314598915865?var=613137180576) — candidate rack; maybe go taller than 37HE
- [Gigabyte MZ32-AR0 Rev1.0 + EPYC 7282 16-Kern 2.8GHz](https://www.ebay.de/itm/358886890399) — mainboard+CPU bundle matching the spec above. Still needs RAM — prefer older/used DDR4 RDIMM over new, it's cheaper.

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## 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