AWS r8g.metal-24xlvsAWS r8gd.12xlarge

r8g.metal-24xl pairs 96 vCPUs with 768GB of RAM at $5.6554/hr On-Demand (about $4072/mo at 24×7). r8gd.12xlarge pairs 48 vCPUs with 384GB at $3.5270/hr (~$2539/mo). r8gd.12xlarge is 38% cheaper per hour than r8g.metal-24xl ($2.1283/hr gap).

Both are generation-8 memory-optimized instances, but they run on different silicon: **r8g.metal-24xl** is AWS Graviton (ARM64), **r8gd.12xlarge** is AWS Graviton (ARM64). 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 r8gd.12xlarge delivers ~60% more single-thread Sysbench score per dollar (590 vs 944 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 (319512 vs 159724) are what to weigh. Spot pricing flips many of these comparisons — when r8g.metal-24xl drops to $1.5269/hr and r8gd.12xlarge drops to $0.9565/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick r8g.metal-24xl when your workload is closer to memory-optimized (memory-bound work — in-memory databases, real-time analytics, large caches). Pick r8gd.12xlarge 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.