AWS c8gn.16xlargevsAWS c8i.16xlarge

c8gn.16xlarge pairs 64 vCPUs with 128GB of RAM at $3.7920/hr On-Demand (about $2730/mo at 24×7). c8i.16xlarge pairs 64 vCPUs with 128GB at $2.9987/hr (~$2159/mo). c8i.16xlarge is 21% cheaper per hour than c8gn.16xlarge ($0.7933/hr gap).

Both are generation-8 compute-optimized instances, but they run on different silicon: **c8gn.16xlarge** is AWS Graviton (ARM64), **c8i.16xlarge** is Intel Xeon (x86_64). AMD variants (suffix `a`) are typically 10% cheaper than Intel siblings at comparable single-thread performance. Graviton variants (suffix `g`) are usually 20–40% cheaper but require ARM64-compatible binaries — most modern Linux stacks are fine, but verify any compiled extensions, native modules, or third-party binaries before migrating. Same vCPU/RAM ratio, same network performance class, different processor.

On raw price-per-performance, the two are c8i.16xlarge delivers ~26% more single-thread Sysbench score per dollar (878 vs 1107 points per $1/hr). That's the cleanest signal we have for "which one runs your workload faster per dollar," but it only matters if your workload is single-thread-bound; for parallel workloads the multi-core scores (213037 vs 112072) are what to weigh. Spot pricing flips many of these comparisons — when c8gn.16xlarge drops to $0.8539/hr and c8i.16xlarge drops to $1.0320/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick c8gn.16xlarge when your workload is closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). Pick c8i.16xlarge when it's closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). When neither side is obviously right, the cheaper hourly rate usually wins for fault-tolerant batch workloads, while the higher single-core score usually wins for latency-sensitive web traffic. The regional pricing tables linked from each instance page below show where each is currently cheapest — sometimes a >20% regional gap flips the comparison entirely.