AWS r7i.xlargevsAWS r7iz.2xlarge

r7i.xlarge pairs 4 vCPUs with 32GB of RAM at $0.2646/hr On-Demand (about $191/mo at 24×7). r7iz.2xlarge pairs 8 vCPUs with 64GB at $0.7440/hr (~$536/mo). r7i.xlarge is 181% cheaper per hour than r7iz.2xlarge ($0.4794/hr gap).

Both are generation-7 memory-optimized instances, but they run on different silicon: **r7i.xlarge** is Intel Xeon (x86_64), **r7iz.2xlarge** 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 r7i.xlarge delivers ~174% more single-thread Sysbench score per dollar (12400 vs 4528 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 (6722 vs 13813) are what to weigh. Spot pricing flips many of these comparisons — when r7i.xlarge drops to $0.0775/hr and r7iz.2xlarge drops to $0.3235/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick r7i.xlarge when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r7iz.2xlarge 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.