AWS c6i.8xlargevsAWS c6id.12xlarge

c6i.8xlarge pairs 32 vCPUs with 64GB of RAM at $1.3600/hr On-Demand (about $979/mo at 24×7). c6id.12xlarge pairs 48 vCPUs with 96GB at $2.4192/hr (~$1742/mo). c6i.8xlarge is 78% cheaper per hour than c6id.12xlarge ($1.0592/hr gap).

Both are generation-6 compute-optimized instances, but they run on different silicon: **c6i.8xlarge** is Intel Xeon (x86_64), **c6id.12xlarge** 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 c6i.8xlarge delivers ~78% more single-thread Sysbench score per dollar (2189 vs 1231 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 (49539 vs 74358) are what to weigh. Spot pricing flips many of these comparisons — when c6i.8xlarge drops to $0.4551/hr and c6id.12xlarge drops to $0.6610/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick c6i.8xlarge when your workload is closer to compute-optimized (CPU-bound work — batch processing, web servers under sustained load, game servers). Pick c6id.12xlarge 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.