B300 vs RTX 4090: Specs, VRAM & Price
Short answer: choose the B300 when 288 GB of VRAM is the gating requirement. Choose the RTX 4090 when 24 GB is enough for the workload and the lower hourly rate points that way.
The B300 has 288 GB of VRAM; the RTX 4090 has 24 GB.
You can rent both by the hour, no purchase required. B300 from $9.89/GPU/hr; RTX 4090 from $0.374/GPU/hr. The RTX 4090 is 96% cheaper at the entry rate.
B300
Good for training and serving frontier-scale LLMs
RTX 4090
Good for inference and light fine-tuning workloads
Last updated: 2026-10-10 21:04:38 UTCRefreshes hourly
Specs side by side
| Spec | B300 | RTX 4090 |
|---|---|---|
| VRAM | 288 GB | 24 GB |
| Memory bandwidth | – | 1,008 GB/s |
| Architecture | Blackwell Ultra | Ada Lovelace |
| Compute capability | 10.3 | 8.9 |
| Precisions in hardware | FP32, FP16, BF16, FP8, INT4 | FP32, FP16, BF16, FP8, INT4 |
| Max board power (TDP) | – | 450W |
| Form factor | – | PCIe 4.0 x16 |
| Regions | 1 | 3 |
On-demand price
| Rate | B300 | RTX 4090 |
|---|---|---|
| Lowest per GPU/hr | $9.89/GPU/hr | $0.761/GPU/hr |
Which is better for AI: B300 or RTX 4090?
Choose the B300 when 288 GB of VRAM is the gating requirement. Choose the RTX 4090 when 24 GB is enough for the workload and the lower hourly rate points that way.
B300 vs RTX 4090: common questions
Is the B300 or the RTX 4090 better for AI?
Short answer: choose the B300 when 288 GB of VRAM is the gating requirement. Choose the RTX 4090 when 24 GB is enough for the workload and the lower hourly rate points that way.
Is the B300 or the RTX 4090 cheaper to rent?
On Aquanode's live marketplace the B300 starts at $9.89/GPU/hr (median $9.89/GPU/hr) and the RTX 4090 starts at $0.374/GPU/hr (median $0.767/GPU/hr). The RTX 4090 is the cheaper of the two at the entry rate, by 96%.
What is the difference between the B300 and the RTX 4090?
The B300 has 288 GB of VRAM against the RTX 4090's 24 GB; the B300 is a Blackwell Ultra part and the RTX 4090 is Ada Lovelace (compute capability 10.3 vs 8.9); both run BF16, FP8, INT4 workloads in hardware. On price, the B300 lists from $9.89/GPU/hr and the RTX 4090 from $0.374/GPU/hr.
How widely available are the B300 and the RTX 4090?
The B300 is listed in 1 region and the RTX 4090 in 3 regions right now.
How much does 1,000 GPU-hours cost on the B300 vs the RTX 4090?
At the lowest rates listed today, 1,000 GPU-hours costs $9,889 on the B300 and $374 on the RTX 4090, a difference of $9,515 for the same runtime. Rates are per GPU per hour and update hourly.
How much VRAM does the B300 have compared to the RTX 4090?
The B300 has 288 GB of VRAM; the RTX 4090 has 24 GB.
How this comparison is calculated
Every price is normalized to a per-GPU hourly rate using the same pipeline as every other pricing surface on Aquanode, and only the cheapest qualifying offer per provider is shown. A dash means that provider does not currently list that GPU.
Architecture, compute capability and supported precisions come from each vendor's published datasheet for that generation, not from the marketplace feed. This page regenerates at most once per hour.
Memory bandwidth, tensor TFLOPS, NVLink/interconnect and max board power are the same verified-from-datasheet figures shown on each model's own B300 page and RTX 4090 page, which link the primary vendor source for that model. A dash here means Aquanode hasn't verified that figure from a primary source yet, never a guess.
Go further
Check what fits in each card's memory with the B300 VRAM calculator and the RTX 4090 VRAM calculator, or browse every model by generation in the GPU index.
More B300 comparisons
More RTX 4090 comparisons
Related reading: H100 pricing and specs, H100 vs H200, A100 vs H100, H100 and H200: SXM vs NVL vs PCIe, and The best GPUs for AI, ranked.
