A100 80GB vs RTX 5090
A100 80GB has 2.5× the memory; RTX 5090 rents for 1.6× less.
The NVIDIA A100 80GB (Ampere, 2020) and the NVIDIA RTX 5090 (Blackwell, 2025) are an odd couple on paper, the A100 80GB is datacenter silicon and the RTX 5090 is a consumer flagship, and the price gap is exactly why people cross-shop them. On capacity, the A100 80GB carries 2.5x the memory (80 vs 32 GB), which sets what each can hold at all. Bandwidth is nearly even (2 vs 1.79 TB/s), so serving speed per GPU will be similar. Raw compute favors the A100 80GB by 1.5x, which matters for training, prefill-heavy traffic, and diffusion work more than for chat-style decoding. The RTX 5090 also speaks native FP8 while the A100 80GB tops out at BF16/INT8, a generational gap explained in CUDA cores vs Tensor Cores.
Price is where it settles: the RTX 5090 rents from $0.54/hr against $0.87/hr for the A100 80GB, a 1.6x gap that the performance numbers above only partly close. Per gigabyte of VRAM, the A100 80GB is the cheaper rental, worth knowing if your model is capacity-bound rather than speed-bound. Bear in mind the RTX 5090 is a consumer card rented mostly through marketplaces, with the trust and reliability trade-offs that implies, while the A100 80GB is datacenter silicon with ECC HBM and standard hosting. For why Ampere remains the value benchmark this comparison is priced against, see The A100 in 2026. Everything below is the underlying data.
NVIDIA · Ampere · 2020
NVIDIA A100 80GB
The GPU that started the LLM era, now a value pick for fine-tuning and mid-size inference.
From $0.87/hr at Vast.ai
NVIDIA · Blackwell · 2025
NVIDIA RTX 5090
The fastest thing you can put in a desktop: 32 GB of GDDR7 at 1.8 TB/s.
From $0.54/hr at Vast.ai
Head to head
■ A100 80GB ■ RTX 5090, bars share one scale across the whole catalog.
| A100 80GB | RTX 5090 | |
|---|---|---|
| Memory | 80 GB HBM2e | 32 GB GDDR7 |
| Bandwidth | 2 TB/s | 1.79 TB/s |
| FP16 dense | 312 TF | 210 TF |
| FP8 dense | - | 420 TF |
| TDP | 400 W | 575 W |
| Interconnect | NVLink 3 · 600 GB/s | PCIe Gen5 |
| Cheapest rental | $0.87/hr | $0.54/hr |
| $/hr per GB VRAM | $1.1¢ | $1.7¢ |
What one can run that the other can't
Only on A100 80GB
- Llama 3.3 70B (4-bit)
- Qwen2.5 72B (4-bit)
- Mixtral 8x7B (8-bit)
Only on RTX 5090
Nothing, A100 80GB runs everything RTX 5090 does.
Rule of thumb: for LLM serving, prefer the GPU with more memory bandwidth per dollar; for training and prefill-heavy work, prefer FLOPS per dollar; and if the model doesn't fit in VRAM, none of the other numbers matter. Sanity-check with the VRAM calculator.