A100 80GB vs RTX 4090

The NVIDIA A100 80GB (Ampere, 2020) and the NVIDIA RTX 4090 (Ada Lovelace, 2022) are an odd couple on paper, the A100 80GB is datacenter silicon and the RTX 4090 is a consumer flagship, and the price gap is exactly why people cross-shop them. On capacity, the A100 80GB carries 3.3x the memory (80 vs 24 GB), which sets what each can hold at all. On memory bandwidth, the number that governs LLM serving speed, the A100 80GB leads at 2 vs 1.01 TB/s. Raw compute favors the A100 80GB by 1.9x, which matters for training, prefill-heavy traffic, and diffusion work more than for chat-style decoding. The RTX 4090 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 4090 rents from $0.34/hr against $0.87/hr for the A100 80GB, a 2.6x 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 4090 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.