NVIDIA A100 40GB vs NVIDIA A100 80GB

Analysis

The NVIDIA A100 40GB and 80GB are the same GA100 die in two different memory configurations, not a generational upgrade — a straight capacity-and-bandwidth choice within the same Ampere-era card. The 40GB ships with older HBM2; the 80GB variant uses newer HBM2e, so upgrading isn't just about doubling VRAM.

Doubling capacity from 40GB to 80GB also buys a real bandwidth jump: 1,555 GB/s to 2,039 GB/s, a 31% gain purely from the HBM2-to-HBM2e memory switch, with no change to the compute silicon underneath. That compounds directly into decode speed — this site's calculator measures Llama 3.1 8B at Q4_K_M running 170.0 tok/s on the 40GB card versus 222.9 tok/s on the 80GB card, tracking the bandwidth gap almost exactly. Capacity is where the functional difference really shows up: the 40GB card only fits Llama 3.3 70B at the most aggressive Q2_K (32.88 GB, 34.4 tok/s), while the 80GB card reaches all the way up to Q6_K (67.37 GB, 22.0 tok/s) — four rungs higher on the quantization ladder for meaningfully better output quality. Across the 85 tracked models, the 80GB card runs 59 natively versus the 40GB card's 51.

Bottom line: If your budget allows it, the 80GB card is the better buy outright — more capacity, more bandwidth, and no compute-architecture tradeoff to weigh, since it's the identical GA100 die underneath. The 40GB card earns its keep on price: it's the cheaper way into genuine HBM-class datacenter hardware, and it's comfortable for 7B-14B models at high quantization or 32B models at Q4-Q6 — workloads that never needed the 80GB ceiling in the first place. Only step up to the 80GB card if 70B-class models at higher quantization, or running several mid-size models loaded simultaneously, are actually part of your workload.