Short answer: choose L40S when a qualified PCIe server needs 48GB, Ada-generation inference/media capabilities, vGPU support or display outputs. Choose H100 only when an 80GB/94GB Hopper accelerator, MIG or an NVLink/NVSwitch platform solves a measured requirement. Both are data-center products, but H100 PCIe, SXM and NVL remain different purchases.
The decision in one minute
- L40S 48GB: Ada capability 8.9, 48GB GDDR6 ECC, 864GB/s, 350W, passive PCIe server card, display/media/vGPU features, no MIG or NVLink.
- H100 PCIe 80GB: Hopper capability 9.0, 80GB HBM2e, 2TB/s, up to 350W, passive PCIe accelerator with MIG.
- H100 SXM 80GB: 80GB HBM3, 3.35TB/s, up to 700W, for compatible HGX/DGX platforms with high-speed interconnect.
- H100 NVL 94GB: 94GB HBM3, 3.9TB/s, configurable 350–400W, dual-slot air-cooled PCIe data-center product.
L40S vs H100 specifications
| Hardware | Architecture / capability | Memory / bandwidth | Power | Deployment clues |
|---|---|---|---|---|
| NVIDIA L40S | Ada / 8.9 | 48GB GDDR6 ECC / 864GB/s | 350W | Passive PCIe server card; display, NVENC/NVDEC and vGPU support; no MIG/NVLink |
| H100 PCIe | Hopper / 9.0 | 80GB HBM2e / 2TB/s | 350W maximum | Passive 10.5-inch dual-slot PCIe accelerator; MIG |
| H100 SXM | Hopper / 9.0 | 80GB HBM3 / 3.35TB/s | Up to 700W | SXM module for compatible HGX/DGX; MIG and NVLink/NVSwitch platform |
| H100 NVL | Hopper / 9.0 | 94GB HBM3 / 3.9TB/s | 350–400W | Dual-slot air-cooled PCIe data-center product; MIG and paired-NVL configuration |
L40S emphasizes inference, graphics, media and virtual-workstation use in a PCIe server. H100 emphasizes Hopper compute, partitioning and scale-up deployments. Validate the exact driver, CUDA, framework, kernels, vGPU or AI Enterprise licensing, hypervisor and host qualification rather than assuming every product-family feature is included.
Exact Qwen3.5 capacity boundaries
Margins below subtract decimal file totals from nominal decimal memory. They exclude KV cache, hybrid-attention state, vision processing, allocator behavior and temporary buffers. A positive remainder is not proof of runtime fit.
| Artifact | Files | L40S 48GB | H100 80GB | H100 NVL 94GB |
|---|---|---|---|---|
| Qwen3.5-35B-A3B Q8_0 + F16 projector | 37.802GB | 10.198GB | 42.198GB | 56.198GB |
| Qwen3.5-35B-A3B official BF16 | 71.904GB | Does not fit files | 8.096GB — bounded | 22.096GB |
| Qwen3.5-122B-A10B Q4_K_M + projector | 77.446GB | Does not fit files | 2.554GB — unsafe | 16.554GB |
| Qwen3.5-122B-A10B official GPTQ-Int4 | 78.864GB | Does not fit files | 1.136GB — unsafe | 15.136GB |
| Qwen3.5-122B FP8 / Q8 + projector / BF16 | 127.163 / 130.781 / 250.173GB | Does not fit files | Does not fit files | Does not fit files |
H100 80GB changes the listed 35B BF16 file-fit result but leaves only 1.136GB/2.554GB for the two listed 122B 4-bit paths, which is unsafe before runtime state. H100 NVL 94GB improves those margins to 15.136GB/16.554GB. None of these devices holds the listed 122B FP8, Q8-plus-projector or BF16 files. Capacity does not establish throughput.
Cooling and platform identity come first
- L40S and H100 PCIe are passive server cards. Both require documented directed chassis airflow; an open tower is not validation.
- H100 SXM is not PCIe. A bare module requires the matching baseboard, cooling, power, firmware and management stack.
- H100 NVL is a separate 94GB product. Confirm qualified chassis, power mode and paired-NVL details rather than treating every “H100” listing as equivalent.
- MIG: H100 may expose only a slice to the process. L40S does not support MIG. Record visible memory and profile.
- Interconnect: L40S has no NVLink; H100 support depends on variant/platform. Software must explicitly partition or parallelize a multi-GPU workload.
Which should you buy?
- Choose L40S when the complete measured workload fits 48GB and the server benefits from Ada inference/media/vGPU capabilities or display connectivity.
- Choose H100 PCIe 80GB when extra capacity or MIG solves a requirement and passive PCIe integration is already qualified.
- Choose H100 SXM only as part of a compatible HGX/DGX platform whose topology, power, cooling and software are justified.
- Choose H100 NVL 94GB when the additional 14GB over ordinary H100 materially changes the measured workload and its qualified PCIe/NVL system is available.
Create the missing controlled comparison
The current fixed database has no accepted L40S or H100 observations. Load either exact configuration starter, then record the complete host, airflow, exposed memory, MIG/interconnect, driver/CUDA, artifact, runtime, context, concurrency, timing definition and peak use. Nothing is saved or submitted automatically.
Used-market checklist
- Verify the exact label and part number: L40S, H100 PCIe 80GB, H100 SXM 80GB or H100 NVL 94GB.
- Request current device identity, visible memory, health/error evidence, power mode and any MIG state.
- Document the complete host, directed airflow, power delivery, PCIe lanes or SXM platform—not only the accelerator.
- Confirm driver/runtime support and any vGPU, AI Enterprise or virtualization licensing.
- Compare delivered-system cost, warranty and return terms through the screened-offers directory and used-hardware checklist.
Continue: read the L40S platform guide, H100 variant guide, 48GB vs 80GB capacity guide, VRAM calculator, or save private criteria and follow RSS.
Sources and limits
- NVIDIA L40S specifications
- NVIDIA H100 product page
- NVIDIA H100 GPU datasheet
- NVIDIA H100 PCIe board specification
- NVIDIA MIG supported-GPU table
- Qwen3.5-35B file provenance and Qwen3.5-122B file provenance
Reviewed October 25, 2026. Specifications are sourced from NVIDIA and may vary by SKU, revision and configured power mode. HighVRAM has not independently benchmarked an L40S–H100 pair. Used configurations and prices change.
Comparing the older 48GB Ampere path? Read A40 versus H100 for the CPU-power, NVLink, vGPU/display and used-system distinctions that differ from L40S.
Desktop alternative: compare RTX 5090 32GB with H100 80GB/94GB before choosing a passive server deployment.
DGX Spark vs H100: Add DGX Spark to the H100 alternative shortlist in the exact capacity and platform comparison.