AWS r7i.12xlargevsAWS r7iz.metal-16xl

r7i.12xlarge pairs 48 vCPUs with 384GB of RAM at $3.1752/hr On-Demand (about $2286/mo at 24×7). r7iz.metal-16xl pairs 64 vCPUs with 512GB at $5.9520/hr (~$4285/mo). r7i.12xlarge is 87% cheaper per hour than r7iz.metal-16xl ($2.7768/hr gap).

Both are generation-7 memory-optimized instances, but they run on different silicon: **r7i.12xlarge** is Intel Xeon (x86_64), **r7iz.metal-16xl** 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.

Benchmark data for at least one of these instances is still being collected, so a direct performance-per-dollar comparison isn't possible yet. Sysbench scores are pending for r7i.12xlarge and 3389/111395 for r7iz.metal-16xl. Check back as the benchmark queue completes — newer-generation instances typically score 10–30% higher on single-thread and 15–50% higher on multi-core vs the previous generation in the same series.

In practice, pick r7i.12xlarge when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r7iz.metal-16xl when it's closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). 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.