Dual RTX 5090 workstation (2x 32 GB) vs Quad RTX 5090 workstation (4x 32 GB)
Dual RTX 5090 has 64 GB memory, 3,584 GB/s bandwidth, 1,400 W nominal power; Quad RTX 5090 has 128 GB memory, 7,168 GB/s bandwidth, 2,600 W nominal power. Compare model compatibility, like-for-like tokens/sec and ownership cost below.
Dual RTX 5090 workstation (2x 32 GB) · Quad RTX 5090 workstation (4x 32 GB)
Verdict
- throughputThe Quad RTX 5090 workstation (4x 32 GB) delivers approximately 31% higher aggregate decode throughput across 5 like-for-like model configurations (same quantization, runtime, context and inference settings).
- capacityBoth machines run all 8 compared models in their best practical configurations. Compare their quantizations and evidence labels before treating any throughput difference as a hardware result.
- costAt 8 hours a day, the Dual RTX 5090 workstation (2x 32 GB) has approximately 53% lower total monthly cost ($80 against $170), for a C corporation in United States (federal).
- powerThe Quad RTX 5090 workstation (4x 32 GB) draws 2250 W under load against 1180 W for the Dual RTX 5090 workstation (2x 32 GB) — a 1.9× difference that shows up in the electricity line and in how loud and hot the room gets.
- evidenceAll 5 like-for-like throughput rows are estimates. Treat the ranking as indicative and the margins as uncertain.
- recommendationThere is no single answer: the Quad RTX 5090 workstation (4x 32 GB) is faster, the Dual RTX 5090 workstation (2x 32 GB) is cheaper to own, and the Dual RTX 5090 workstation (2x 32 GB) gives more throughput per unit of purchase currency. Pick on whichever constraint actually binds you — interactive latency, monthly budget, or capacity headroom for larger models later.
Every statement above is generated from the calculations on this page by fixed rules — no prose is written for individual comparisons. If the numbers change, the verdict changes with them.
Hardware
| Dual RTX 5090 workstation (2x 32 GB) | Quad RTX 5090 workstation (4x 32 GB) | |
|---|---|---|
| Purchase price estimate | $5,854 * | $12,611 * |
| Memory | 64 GB | 128 GB |
| Theoretical bandwidth (aggregate on multi-GPU) | 3,584 GB/s | 7,168 GB/s |
| Usable bandwidth indicator | interconnect-adjusted per workload | interconnect-adjusted per workload |
| Nominal power | 1400 W | 2600 W |
| Measured load power | 1180 W | 2250 W |
| Idle power | 110 W | 190 W |
| Architecture | 2× GPU | 4× GPU |
Like-for-like performance5 comparable models
Ternary Bonsai 2 27BMixtral 8x7BPhi-3.5 MoE 42B-A6.6BNemotron 3.5 Lightning 30B-A3BQwen3-Coder 30B-A3BQwen3 30B-A3BGemma 4 26B-A4Bgpt-oss-20b
| Model | Dual RTX 5090 workstation (2x 32 GB) | Quad RTX 5090 workstation (4x 32 GB) | Winner |
|---|---|---|---|
| Ternary Bonsai 2 27B 27.36B | — no matched configuration | — no matched configuration | Not comparable |
| Mixtral 8x7B 46.703B (13B active) | — no matched configuration | — no matched configuration | Not comparable |
| Phi-3.5 MoE 42B-A6.6B 41.873B (6.6B active) | — no matched configuration | — no matched configuration | Not comparable |
| Nemotron 3.5 Lightning 30B-A3B 31.578B (3B active) | ~249–359 t/s Q8_0 | ~315–454 t/s Q8_0 | Quad RTX 5090 workstation (4x 32 GB) +26% estimated · estimator_v1 · 8K context |
| Qwen3-Coder 30B-A3B 30.532B (3.3B active) | ~236–339 t/s Q8_0 | ~301–434 t/s Q8_0 | Quad RTX 5090 workstation (4x 32 GB) +28% estimated · estimator_v1 · 8K context |
| Qwen3 30B-A3B 30.532B (3.3B active) | ~236–339 t/s Q8_0 | ~301–434 t/s Q8_0 | Quad RTX 5090 workstation (4x 32 GB) +28% estimated · estimator_v1 · 8K context |
| Gemma 4 26B-A4B 25.806B (3.8B active) | ~139–200 t/s BF16 | ~192–277 t/s BF16 | Quad RTX 5090 workstation (4x 32 GB) +38% estimated · estimator_v1 · 8K context |
| gpt-oss-20b 20.915B (3.6B active) | ~145–208 t/s BF16 | ~199–287 t/s BF16 | Quad RTX 5090 workstation (4x 32 GB) +38% estimated · estimator_v1 · 8K context |
Hardware deltas are calculated only when quantization, runtime, exact context, execution/decode mode and relevant inference settings match. Measured and estimated results are never compared to each other. A difference under 10% is reported as a tie.
Best practical configuration
| Model | Dual RTX 5090 workstation (2x 32 GB) | Quad RTX 5090 workstation (4x 32 GB) | Practical result |
|---|---|---|---|
| Ternary Bonsai 2 27B | — PTQ1_0 · estimated | — PTQ1_0 · estimated | Both fit; configurations may differ |
| Mixtral 8x7B | — Q5_K_M · estimated | — Q8_0 · estimated | Both fit; configurations may differ |
| Phi-3.5 MoE 42B-A6.6B | — Q5_K_M · estimated | — Q8_0 · estimated | Both fit; configurations may differ |
| Nemotron 3.5 Lightning 30B-A3B | ~249–359 t/s Q8_0 · estimated | ~315–454 t/s Q8_0 · estimated | Both fit; configurations may differ |
| Qwen3-Coder 30B-A3B | ~236–339 t/s Q8_0 · estimated | ~301–434 t/s Q8_0 · estimated | Both fit; configurations may differ |
| Qwen3 30B-A3B | ~236–339 t/s Q8_0 · estimated | ~301–434 t/s Q8_0 · estimated | Both fit; configurations may differ |
| Gemma 4 26B-A4B | ~216–311 t/s Q8_0 · estimated | ~281–404 t/s Q8_0 · estimated | Both fit; configurations may differ |
| gpt-oss-20b | ~324–466 t/s MXFP4 · estimated | ~387–556 t/s MXFP4 · estimated | Both fit; configurations may differ |
This is a deployment comparison: each machine uses its own recommended configuration. Different quantizations can change speed and quality, so these figures are not raw hardware benchmarks.
Economics — United States (federal), C corporation, 8h/day
| Dual RTX 5090 workstation (2x 32 GB) | Quad RTX 5090 workstation (4x 32 GB) | |
|---|---|---|
| Purchase price estimate | $5,854 | $12,611 |
| Reclaimable VAT | $0 | $0 |
| Net cash at purchase | $5,854 | $12,611 |
| Monthly depreciation | $82.94 | $178.65 |
| Monthly electricity | $7.98 (57 kWh) | $14.83 (106 kWh) |
| Tax programme | §179 100.0% | §179 100.0% |
| Tax-programme benefit | $1,229 | $2,648 |
| Monthly economic cost | $79.98 | $170.40 |
| Total over 5 years | $4,799 | $10,224 |
Purchase prices are localized inputs in USD: tax/VAT excluded for Dual RTX 5090 workstation (2x 32 GB) and tax/VAT excluded for Quad RTX 5090 workstation (4x 32 GB). Net cash and monthly economic cost then apply the selected United States (federal) / C corporation tax treatment. Tax assumptions last verified 2026-09-07. Federal planning estimate only, not tax advice. State and local income tax, sales/use tax and incentives are excluded. It assumes 100% business use, a Section 179 election, enough business income to use it, and that the full annual limit remains available.