REDDIT · REDDIT// 6h agoINFRASTRUCTURE

Dual RTX 3090 X399 Rig Tempts Buyers

A Reddit user is evaluating whether an older X399 Threadripper build with two RTX 3090s, 128 GB of RAM, and water cooling is still worth buying for local AI workloads. The asking price is about 2100€, which makes the GPUs the main value driver, but the poster is concerned about whether the platform can handle a 4-GPU setup and whether the idle power draw will be too expensive in Denmark.

// ANALYSIS

Hot take: this is a decent GPU-first buy if the cards are healthy, but it is not a great long-term platform choice if you care about efficiency or expansion.

–The main value is the pair of RTX 3090s; the rest of the system is basically a bonus.
–X399/Threadripper 2950X is old, so PCIe lane flexibility and multi-GPU compatibility are the upside, but single-thread performance and platform efficiency are dated.
–Idle power matters a lot here: an old HEDT board, CPU, chipset, water cooling, and four GPUs can add up fast at 0.4 € / kWh.
–For local LLM work, 2x 3090s is still strong value per euro if you need 24 GB cards and can tolerate the power bill.
–A 4-GPU plan is plausible mechanically, but thermals, PSU sizing, risers, spacing, and motherboard lane layout become the real risks.

// TAGS

x399threadripperrtx3090multigpullmlocalaiworkstationpowerconsumption

DISCOVERED

6h ago

2026-04-24

PUBLISHED

8h ago

2026-04-24

RELEVANCE

7/ 10

AUTHOR

ziphnor