GPU comparison
Rubin CPX vs B300: specs and rental prices
NVIDIA Rubin CPX against NVIDIA B300: 128 GB against 270 GB of memory. Specs from NVIDIA, prices as of Oct 29, 2026.
In short
- The B300 lists 270 GB of GPU memory against 128 GB for the Rubin CPX: 2.11× higher.
- Memory type is GDDR7 on the Rubin CPX and HBM3E on the B300.
- Not every figure can be compared: at least one vendor page does not publish: Memory bandwidth; FP8 tensor throughput; FP16 / BF16 tensor throughput; TF32 tensor throughput; FP64 throughput; Maximum power; GPU-to-GPU interconnect.
- Only the B300 has a fresh on-demand listing ($7.40 per GPU-hour at Hyperstack); the Rubin CPX has none right now.
This summary is generated from the tables below. Prices were last checked Oct 29, 2026. A listing not re-checked for 7 days is greyed and left out of every lowest-price figure; after 14 days it is removed from the page.
Specifications side by side
| Specification | Rubin CPX | B300, per GPU (HGX B300) | Difference |
|---|---|---|---|
| GPU memory | 128 GB | 270 GB | B300 2.11× higher |
| Memory type | GDDR7 | HBM3E | Different |
| Memory bandwidth | Not published | 7,700 GB/s | — |
| FP8 tensor throughput | Not published | 9,000 TFLOPS (with sparsity) | — |
| FP16 / BF16 tensor throughput | Not published | 4,500 TFLOPS (with sparsity) | — |
| TF32 tensor throughput | Not published | 2,200 TFLOPS (with sparsity) | — |
| FP64 throughput | Not published | 1.2 TFLOPS | — |
| Maximum power | Not published | 1,100 W | — |
| GPU-to-GPU interconnect | Not published | 1,800 GB/s | — |
Compared versions: Rubin CPX and B300, per GPU (HGX B300). The figure in the stronger cell is shaded; power is shown without a winner. Two throughput figures are compared only when both vendors state them on the same basis (both with sparsity, or both dense), and “derived” means a total the vendor publishes divided by the GPU count it publishes. Full tables with sources: Rubin CPX specifications · B300 specifications.
Rental prices
| Rental price | Rubin CPX | B300 | Difference |
|---|---|---|---|
| Lowest listed on-demand price | No fresh listing | $7.40 per GPU-hour · Hyperstack · checked Oct 29, 2026 | — |
| Lowest listed spot price | No fresh listing | $0.99 per GPU-hour · Nebius · checked Oct 29, 2026 | — |
| Price per GB of memory | Not available | $0.027 per GB of GPU memory per hour | — |
| Fresh listings | 0 from 0 providers | 13 from 10 providers | — |
Prices cover every version and instance size the providers list, so they are not tied to the versions compared above; the price per GB of memory divides the lowest fresh on-demand price by the memory of the compared version. Listed prices are not like for like across providers. See every listing: Rubin CPX prices · B300 prices.
More on these GPUs
Cite this page
Last updated Oct 29, 2026. Figures may change as records are updated — include the date you retrieved them.
| APA | Data Center Census. (2026). Rubin CPX vs B300. Retrieved from https://datacentercensus.com/gpu-prices/compare/rubin-cpx-vs-b300 |
|---|---|
| MLA | “Rubin CPX vs B300.” Data Center Census, Oct 29, 2026, https://datacentercensus.com/gpu-prices/compare/rubin-cpx-vs-b300. |
| Link | https://datacentercensus.com/gpu-prices/compare/rubin-cpx-vs-b300 |
Republishing a figure or table? Attribute it to Data Center Census with a link to this page. The underlying data is downloadable as JSON and CSV; the press kit has standing figures and contact details.