Amazon Elastic Compute Cloud
User Guide for Windows Instances

Compute Optimized Instances

Compute optimized instances are ideal for compute-bound applications that benefit from high-performance processors. They are well suited for the following applications:

  • Batch processing workloads

  • Media transcoding

  • High-performance web servers

  • High-performance computing (HPC)

  • Scientific modeling

  • Dedicated gaming servers and ad serving engines

  • Machine learning inference and other compute-intensive applications

Hardware Specifications

The following is a summary of the hardware specifications for compute optimized instances.

Instance type Default vCPUs Memory (GiB)
c4.large 2 3.75
c4.xlarge 4 7.5
c4.2xlarge 8 15
c4.4xlarge 16 30
c4.8xlarge 36 60
c5.large 2 4
c5.xlarge 4 8
c5.2xlarge 8 16
c5.4xlarge 16 32
c5.9xlarge 36 72
c5.18xlarge 72 144
c5d.large 2 4
c5d.xlarge 4 8
c5d.2xlarge 8 16
c5d.4xlarge 16 32
c5d.9xlarge 36 72
c5d.18xlarge 72 144

For more information about the hardware specifications for each Amazon EC2 instance type, see Amazon EC2 Instance Types.

For more information about specifying CPU options, see Optimizing CPU Options.

Instance Performance

EBS-optimized instances enable you to get consistently high performance for your EBS volumes by eliminating contention between Amazon EBS I/O and other network traffic from your instance. C4, C5, and C5d instances are EBS-optimized by default at no additional cost. For more information, see Amazon EBS–Optimized Instances.

Network Performance

You can enable enhanced networking capabilities on supported instance types. Enhanced networking provides significantly higher packet-per-second (PPS) performance, lower network jitter, and lower latencies. For more information, see Enhanced Networking on Windows.

Instance types that use the Elastic Network Adapter (ENA) for enhanced networking deliver high packet per second performance with consistently low latencies. Most applications do not consistently need a high level of network performance, but can benefit from having access to increased bandwidth when they send or receive data. Instance types that use the ENA and support up to 10 Gbps of throughput use a network I/O credit mechanism to allocate network bandwidth to instances based on average bandwidth utilization. These instances accrue credits when their network throughput is below their baseline limits, and can use these credits when they perform network data transfers. For workloads that require access to 10 Gbps of bandwidth or more on a sustained basis, we recommend using instance types that support 10 Gbps or 25 Gbps network speeds.

The following is a summary of network performance for compute optimized instances that support enhanced networking.

Instance type Network performance Enhanced networking

c5.4xlarge and smaller | c5d.4xlarge and smaller

Up to 10 Gbps ENA
c5.9xlarge | c5d.9xlarge 10 Gbps ENA
c5.18xlarge | c5d.18xlarge 25 Gbps ENA
c4.large Moderate Intel 82599 VF
c4.xlarge | c4.2xlarge | c4.4xlarge High Intel 82599 VF
c4.8xlarge 10 Gbps Intel 82599 VF

Instance Features

The following is a summary of features for compute optimized instances:

VPC only EBS only Placement group









C5d Yes Yes

For more information, see the following:

Release Notes

  • C4, C5, and C5d instances require 64-bit EBS-backed HVM AMIs. They have high-memory (up to 144 GiB of RAM), and require a 64-bit operating system to take advantage of that capacity. HVM AMIs provide superior performance in comparison to paravirtual (PV) AMIs on high-memory instance types. In addition, you must use an HVM AMI to take advantage of enhanced networking.

  • C5 and C5d instances have the following requirements:

    • Must have the NVMe drivers installed. EBS volumes are exposed as NVMe block devices.

    • Must have the Elastic Network Adapter (ENA) drivers installed.

    The following AMIs meet these requirements:

    • Amazon Linux 2

    • Amazon Linux AMI 2014.03 or later

    • Ubuntu 14.04 or later

    • SUSE Linux Enterprise Server 12 or later

    • Red Hat Enterprise Linux 7.4 or later

    • CentOS 7 or later

    • FreeBSD 11.1-RELEASE

    • Windows Server 2008 R2 or later

  • C5 instances support a maximum of 27 EBS volumes plus elastic network interface attachments. For example, c5.2xlarge instances support four network interfaces. Every instance has at least one network interface. If you have a c5.2xlarge instance with three additional elastic network interface attachments, you can attach 24 EBS volumes to that instance.

  • The c5d.18xlarge instance type supports a maximum of 25 EBS volumes plus elastic network interface attachments. Other sizes of C5d instances support a maximum of 26 EBS volumes plus elastic network interfaces.

  • ClassicLink is not supported for C5 and C5d instances—you cannot use ClassicLink to link your EC2-Classic instances to these instances in your VPC.

  • There is a limit on the total number of instances that you can launch in a region, and there are additional limits on some instance types. For more information, see How many instances can I run in Amazon EC2?. To request a limit increase, use the Amazon EC2 Instance Request Form.