L40S vs RTX 4090
Both run on the same nodes, the same templates and the same tiers here — so the choice comes down to memory, bandwidth and price. Every figure below is from the catalogue or the vendor datasheet.
- L40S
- $0.15/h48 GB · Ada Lovelace · 96 available
- RTX 4090
- $0.06/h24 GB · Ada Lovelace · 128 available
- Price gap
- 60%On spot, per GPU-hour
- Over 100 h
- $9.00Difference for the same GPU-hours
What actually separates them.
Four differences that change a decision, computed from the numbers rather than asserted.
Bigger models fit on the L40S
48 GB against 24 GB. At FP16 that is about 19B parameters on one GPU, against 9B.
The RTX 4090 costs 60% less per hour
$0.06 against $0.15 on spot — $9.00 of difference over 100 GPU-hours.
Token generation is faster on the RTX 4090
1,008 GB/s against 864 GB/s. Inference reads the whole model from memory for every token, so bandwidth, not FLOPS, usually sets the ceiling.
More memory per dollar on the RTX 4090
400 GB per dollar per hour against 320 GB. The usual tie-breaker when both cards fit the job.
Every figure we hold on both cards.
A row is marked only when both values exist and one is genuinely better. L40S leads on 4 rows, RTX 4090 on 5.
| L40S | RTX 4090 | |
|---|---|---|
| GPU memoryDecides which models fit at all | 48 GB GDDR6 | 24 GB GDDR6X |
| Memory bandwidthSets token throughput on inference | 864 GB/s | 1,008 GB/s |
| FP32 | 92 TFLOPS | 83 TFLOPS |
| 8-bit float (FP8)Halves the memory a model needs, where the stack supports it | Supported | Supported |
| Architecture | Ada Lovelace (2023) | Ada Lovelace (2022) |
| Board powerLower is cheaper to run at scale — for us, not for your bill | 350 W | 450 W |
| GPU-to-GPU linkOnly matters for multi-GPU training | PCIe only | PCIe only |
| Node sizes | 1×, 2×, 4×, 8× | 1×, 2×, 4× |
| Spot price | $0.15/h | $0.06/h |
| On-demand price | $0.25/h | $0.09/h |
| Memory per dollarGPU memory per $1 of spot time, per hour | 320 GB | 400 GB |
| 30-day reclaim rateShare of spot instances reclaimed | <5% | 10–15% |
| Available now | 96 GPUs | 128 GPUs |
Specifications come from each vendor's datasheet — linked on the L40S page and the RTX 4090 page. Prices are ours, per GPU-hour, billed per minute.
The same models, on one GPU of each.
Weights only, with 20% of the memory kept free for activations and the KV cache. A cross means one GPU is not enough — the model page has the multi-GPU arithmetic.
| Model | Precision | L40S 48 GB | RTX 4090 24 GB |
|---|---|---|---|
| Llama 3.1 8B8B parameters | FP16 · 16 GB | Fits | Fits |
| FP8 · 8 GB | Fits | Fits | |
| INT4 · 4 GB | Fits | Fits | |
| Qwen2.5 32B32B parameters | FP16 · 64 GB | Needs 2× node | Needs 4× node |
| FP8 · 32 GB | Fits | Needs 2× node | |
| INT4 · 16 GB | Fits | Fits | |
| Llama 3.3 70B70B parameters | FP16 · 140 GB | Needs 4× node | Needs more than one node |
| FP8 · 70 GB | Needs 2× node | Needs 4× node | |
| INT4 · 35 GB | Fits | Needs 2× node | |
| Mixtral 8x22B141B parameters | FP16 · 282 GB | Needs 8× node | Needs more than one node |
| FP8 · 141 GB | Needs 4× node | Needs more than one node | |
| INT4 · 71 GB | Needs 2× node | Needs 4× node |
The same 100 GPU-hours on each.
Compute only, billed per minute. Storage is $0.08 per GB-month on either card.
| L40S | RTX 4090 | |
|---|---|---|
| One hour, spot | $0.15 | $0.06 |
| One day, spot | $3.60 | $1.44 |
| 100 GPU-hours, spot | $15.00 | $6.00 |
| 100 GPU-hours, on-demand | $25.00 | $9.00 |
| A month, reserved | $109.50 | $43.80 |
Take the L40S when…
- Fine-tuning with LoRA and QLoRA — Comfortable for parameter-efficient training on 13B–34B models without sharding.
- Inference servers — Holds 30B-class models quantised, or several smaller models side by side.
- Anything that can checkpoint — On the spot tier this model is 40% below its own on-demand price, with a 2-minute notice before a reclaim.
Take the RTX 4090 when…
- Fine-tuning small models — LoRA on 7B–13B models, and full fine-tuning below 3B.
- Image and video generation — Diffusion pipelines run entirely in memory at this capacity.
- Anything that can checkpoint — On the spot tier this model is 33% below its own on-demand price, with a 2-minute notice before a reclaim.
L40S or RTX 4090?
Which is cheaper, the L40S or the RTX 4090?
The RTX 4090, at $0.06 per GPU-hour on spot against $0.15 — 60% less. On-demand: $0.09 against $0.25.
Which one should I take for inference?
Take the one that holds the model with room for the KV cache, then the one with more memory bandwidth. Here that is the L40S on capacity (48 GB) and the RTX 4090 on bandwidth.
Can I run both on the same job?
Not inside one instance — a node holds GPUs of a single model. You can run two instances in parallel, on the same persistent volume in turn, or split the work: a big card for the model that needs capacity, a cheap one for the parts that do not.
Other comparisons: the full list · all 47 models
Try both for less than the price of deciding.
An hour on each costs $0.21 on spot. Nothing renews, and your disk moves between them.
Billed per minute from the moment the instance is reachable. Minimum credit $40, no subscription.