AWS i3.4xlargevsAWS i3en.3xlarge

i3.4xlarge pairs 16 vCPUs with 122GB of RAM at $1.2480/hr On-Demand (about $899/mo at 24×7). i3en.3xlarge pairs 12 vCPUs with 96GB at $1.3560/hr (~$976/mo). i3.4xlarge is 9% cheaper per hour than i3en.3xlarge ($0.1080/hr gap).

Both are generation-3 storage-optimized (NVMe SSD) instances, but they run on different silicon: **i3.4xlarge** is Intel Xeon (x86_64), **i3en.3xlarge** 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 i3en.3xlarge delivers ~11% more single-thread Sysbench score per dollar (728 vs 806 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 (10771 vs 10075) are what to weigh. Spot pricing flips many of these comparisons — when i3.4xlarge drops to $0.5897/hr and i3en.3xlarge drops to $0.4664/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick i3.4xlarge when your workload is closer to storage-optimized (NVMe SSD) (I/O-bound work needing low-latency NVMe local storage — NoSQL, search). Pick i3en.3xlarge when it's closer to storage-optimized (NVMe SSD) (I/O-bound work needing low-latency NVMe local storage — NoSQL, search). 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.