Instances›AWS EC2›c7i-flex›c7i-flex.16xlarge
Compute
vCPUs64
Memory128 GiB
Mem / vCPU2.00 GiB
ProcessorXeon Scalable
Clock speed3.2 GHz
Architecturex86_64
Storage
TypeEBS only
Bandwidth20,000 Mbps
Throughput2500 MB/s
IOPS80,000
Networking
PerformanceUp to 25 Gigabit
Max ENIs15
IPv6Yes
GPUNone
Family sizes
c7i-flex.large2 vCPU · 4 GiB
c7i-flex.xlarge4 vCPU · 8 GiB
c7i-flex.2xlarge8 vCPU · 16 GiB
c7i-flex.4xlarge16 vCPU · 32 GiB
c7i-flex.8xlarge32 vCPU · 64 GiB
c7i-flex.12xlarge48 vCPU · 96 GiB
c7i-flex.16xlarge64 vCPU · 128 GiB
c7i-flex.16xlarge

The c7i-flex.16xlarge is a compute-optimized AWS EC2 instance: 64 vCPU and 128 GiB of memory, 2.00 GiB per vCPU. It runs on Intel Xeon Scalable (Sapphire Rapids) at 3.2 GHz, and AWS introduced it in January 2025. No single Spot node covers 64 vCPU and 128 GiB, so the equivalent is a fleet: 4 × ch.vs1.2xlarge, 64 vCPU and 128 GiB in total, about 94% below the US East (N. Virginia) on-demand rate. Spot delivers compute as managed Kubernetes, so a node pool of that size is the native shape of the answer rather than a workaround — provided the workload scales horizontally.

Match qualityScale-out match

c7i-flex.16xlarge gives you 64 vCPU and 128 GiB in a single machine. The largest comparable Spot node, ch.vs1.2xlarge, is 16 vCPU and 32 GiB, so the equivalent here is 4 nodes rather than one.

Spot runs as managed Kubernetes, so a 4-node pool is the normal way to run things rather than a workaround. If your workload already sits behind a load balancer, a queue or a scheduler, it spreads across them without changes. If it needs all 64 cores and 128 GiB in one process, it does not.

Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$2.713$0.620$1.795$1.194$0.164
$2.549 savings
US Central, Chicagono AWS region$0.044
US Central, Dallasno AWS region$0.444
Hong Kong$3.447$2.280$1.564$0.164
$3.283 savings
Sydney, Australia$3.543$1.059$2.339$1.610$0.164
$3.379 savings
London, UK$3.224$0.322$2.128$1.465$0.524
$2.700 savings
US West, San Jose$3.384$0.736$2.235$1.538$0.008
$3.376 savings
US Central, Dallas 2no AWS region$0.488
US East, N. Virginia 2$2.713$0.620$1.795$1.194$0.648
$2.065 savings
When to use it
Good for
  • ●Scientific modelling and simulation
  • ●Ad serving and real-time bidding
  • ●Game servers and matchmaking
  • ●Workloads that fit inside 128 GiB of RAM
  • ●Parallel work that can occupy 64 vCPU
  • ●Network-heavy services — AWS rates this size at Up to 25 Gigabit
  • ●Anything that shards cleanly across 4 nodes, which is how it maps onto Rackspace Spot
Avoid if
  • ●The working set needs more than 128 GiB of RAM
  • ●More than 2.00 GiB of RAM per vCPU is needed — that ratio is fixed for the whole family
  • ●The work is single-threaded. Most of these 64 vCPU would sit idle.
  • ●Local NVMe or instance-store disk is a hard requirement
  • ●GPU or FPGA acceleration is needed
  • ●Memory-hungry applications. A memory-optimized family gives more RAM per dollar.
c7i-flex.16xlarge runs $1,981/mo on AWS on-demand. The 4-node equivalent on Rackspace Spot: $120/mo.
  • Spot sells spare capacity at market prices. It is the cheapest compute on the internet.
  • Prices are set by supply and demand. You pay what the market decides.
  • Compute is delivered as fully managed Kubernetes. All infrastructure is taken care of.
  • Egress costs $0.01/GB after the free allowance. AWS charges $0.09/GB.
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