RTX 4090
24GB GDDR6X, $0.34/hr spot, PCIe 4.0 only
L40S
48GB GDDR6, $0.59/hr spot, FP8 native, ECC memory
Head-to-Head Hardware Specs
Side-by-side hardware architecture comparison for RTX 4090 vs L40S.
RTX 4090
L40S
Which GPU Fits Your Workload?
Pre-Training
Neither — both lack NVLink for multi-GPU training
Fine-Tuning
L40S — 48GB enables 30B QLoRA, FP8 for larger batches
Inference
RTX 4090 — $0.34/hr INT4 beats L40S on pure cost/dollar
NVIDIA RTX 4090 vs L40S: Consumer Flagship vs Enterprise Ada for Inference
24GB GDDR6X consumer speed vs 48GB enterprise memory stability: Continuous batching limits, virtualization support, and reliability.
Technical Scorecard
Side-by-side infrastructure specs using live pricing data for RTX 4090-class hardware.
| Metric | RTX 4090 | L40S |
|---|---|---|
| Network Fabric | PCIe 4.0 (64 GB/s) | PCIe 4.0 (64 GB/s) |
| Storage Throughput | Local NVMe (7,000 MB/s) | Local NVMe (7,000 MB/s) |
| Egress Pricing | Provider dependent | Provider dependent |
| SLA Guarantee | Best effort (consumer) | 99.9% (enterprise) |
| 8-GPU 100h Cost | $27.20 (8× RTX 4090 @ $0.34/hr) | $47.20 (8× L40S @ $0.59/hr) |
Live Pricing Comparison
Spot and reserved rates refreshed from provider APIs. Filtered to RTX 4090-class hardware.
| Provider | GPU & VRAM | Interconnect | Spot Rate | On-Demand | Monthly | Status | Action | |
|---|---|---|---|---|---|---|---|---|
Community | PCIe 4.0 (64 GB/s) | $0.34 / hr | $0.85 / hr | $208 / mo | Instant | |||
Bare Metal | PCIe 4.0 (64 GB/s) | $0.69 / hr | $1.73 / hr | $422 / mo | Instant | |||
Cloud | PCIe 4.0 (64 GB/s) | $0.74 / hr | $1.85 / hr | $453 / mo | Instant | |||
Dedicated | PCIe 4.0 (64 GB/s) | $0.89 / hr | $2.23 / hr | $545 / mo | Instant |
When to Choose RTX 4090
- Budget inference for 7B-13B INT4 models
- Development and testing workloads
- Stable Diffusion batch rendering
When to Choose L40S
- Production FP8 inference requiring ECC memory
- 30B parameter models needing 48GB VRAM
- Enterprise workloads requiring virtualization support
Technical Deep-Dive
VRAM & Model Capacity
RTX 4090: 24GB GDDR6X — fits Llama 8B INT4 (4GB) with headroom, but Llama 30B INT4 requires aggressive quantization and context truncation. L40S: 48GB GDDR6 — fits Llama 30B INT4 comfortably, or Llama 70B INT4 with CPU offloading. The 2x VRAM advantage enables larger models and longer context windows.
FP8 Native vs INT4 Only
RTX 4090: No FP8 support — limited to FP16/INT8/INT4. L40S: Native FP8 Tensor Core support at 733 TFLOPS — 4.4x more FP8 throughput than the 4090's FP16 (82.6 TFLOPS). For production inference where FP8 quality matters, the L40S is the only viable option.
Reliability & ECC
RTX 4090: Consumer-grade, no ECC memory, variable thermal conditions on cloud hosts. L40S: Enterprise-grade, ECC memory for bit-flip detection, consistent datacenter thermals. For production serving SLAs, the L40S's reliability justifies the 74% price premium.
Final Verdict
The RTX 4090 offers lower hourly cost for INT4 inference. The L40S leads on FP8 precision, memory capacity, enterprise reliability, and ECC memory for production workloads.