AWS m5a.8xlargevsAWS m5ad.12xlarge

m5a.8xlarge pairs 32 vCPUs with 128GB of RAM at $1.3760/hr On-Demand (about $991/mo at 24×7). m5ad.12xlarge pairs 48 vCPUs with 192GB at $2.4720/hr (~$1780/mo). m5a.8xlarge is 80% cheaper per hour than m5ad.12xlarge ($1.0960/hr gap).

Both are generation-5 general-purpose instances, but they run on different silicon: **m5a.8xlarge** is AMD EPYC (x86_64), **m5ad.12xlarge** is AMD EPYC (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 m5a.8xlarge delivers ~79% more single-thread Sysbench score per dollar (918 vs 512 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 (20976 vs 31517) are what to weigh. Spot pricing flips many of these comparisons — when m5a.8xlarge drops to $0.6204/hr and m5ad.12xlarge drops to $0.9674/hr, the cheap-per-hour winner can swing meaningfully.

In practice, pick m5a.8xlarge when your workload is closer to general-purpose (balanced general-purpose workloads with a 1:4 vCPU-to-memory ratio). Pick m5ad.12xlarge when it's closer to general-purpose (balanced general-purpose workloads with a 1:4 vCPU-to-memory ratio). 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.