Instances›AWS EC2›c8gb›c8gb.16xlarge
Compute
vCPUs64
Memory128 GiB
Mem / vCPU2.00 GiB
ProcessorGraviton4 Processor
Clock speed2.8 GHz
Architecturearm64
Storage
TypeEBS only
Bandwidth100,000 Mbps
Throughput12500 MB/s
IOPS480,000
Networking
Performance133.33 Gigabit
Max ENIs16
IPv6Yes
GPUNone
Family sizes
c8gb.medium1 vCPU · 2 GiB
c8gb.large2 vCPU · 4 GiB
c8gb.xlarge4 vCPU · 8 GiB
c8gb.2xlarge8 vCPU · 16 GiB
c8gb.4xlarge16 vCPU · 32 GiB
c8gb.8xlarge32 vCPU · 64 GiB
c8gb.12xlarge48 vCPU · 96 GiB
c8gb.16xlarge64 vCPU · 128 GiB
c8gb.24xlarge96 vCPU · 192 GiB
c8gb.metal-24xl96 vCPU · 192 GiB
c8gb.48xlarge192 vCPU · 384 GiB
c8gb.metal-48xl192 vCPU · 384 GiB
c8gb.16xlarge

The c8gb.16xlarge pairs 64 vCPU with 128 GiB of RAM, the 2.00 GiB-per-vCPU ratio that marks a compute-optimized instance. In the name, "c" stands for compute, "8" is the generation, "gb" marks AWS Graviton (ARM) processors and block-storage optimisation and "16xlarge" is the size within the c8gb family. It runs on AWS Graviton4 Processor at 2.8 GHz, and AWS introduced it in December 2025. AWS has since shipped c9g; c9g.16xlarge is the direct replacement at this size, scoring 2,295,964 CoreMark/s against this instance's 1,872,714 — roughly 23% more throughput for the same vCPU count. Spot's node ladder tops out below this size, so c8gb.16xlarge becomes 4 × ch.vs1.2xlarge (64 vCPU, 128 GiB combined), $3.79/hr on AWS in US East (N. Virginia), from $0.164/hr on Rackspace Spot. 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

c8gb.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.

x86_64 onlyc8gb.16xlarge is Graviton (arm64) and Rackspace Spot has no arm64 nodes, so you'd be moving to x86. You'll need x86 builds of your images, and per-core speed differs between the chips — worth testing before you decide how many nodes to run.
Pricing by region
1 hr
RegionAWS on-demandAWS Spot1-yr Reserved3-yr ReservedRackspace SpotYou save
US East, N. Virginia$3.792$0.437$0.164
$3.628 savings
US Central, Chicagono AWS region$0.044
US Central, Dallasno AWS region$0.444
Hong Kong$0.164
Sydney, Australia$0.164
London, UK$0.524
US West, San Jose$4.740$0.657$0.008
$4.732 savings
US Central, Dallas 2no AWS region$0.488
US East, N. Virginia 2$3.792$0.437$0.648
$3.144 savings
When to use it
Good for
  • ●High-traffic web and API serving
  • ●Scientific modelling and simulation
  • ●Ad serving and real-time bidding
  • ●Workloads that fit inside 128 GiB of RAM
  • ●Parallel work that can occupy 64 vCPU
  • ●Network-heavy services — AWS rates this size at 133.33 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
  • ●You cannot rebuild x86-only binaries or vendor images for aarch64
  • ●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.
  • ●More than 2.00 GiB of RAM per vCPU is needed — that ratio is fixed for the whole family
Stop overpaying AWS. This compute costs $2,768/mo on AWS vs $120/mo on Rackspace Spot.
  • 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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