1. Overview

The Graphcore® C600 IPU-Processor card is a dual-slot, full-height PCI Express Gen4 card containing Graphcore’s Mk2 IPU with FP8 support, designed to accelerate machine intelligence applications for both training and inference. All other components are supplied by industry-standard vendors. GC-C600 is the regulatory model for the C600 PCIe card.

The C600 has a thermal design power (TDP) of 185 W running typical workloads and is passively cooled when installed in a suitable chassis enclosure. The maximum power of the card is capped and can be configured to be higher or lower, should that be required.

All the memory on the card is contained within the IPU, providing extremely high bandwidth to the processing cores. There is a total of 900 MB of In-Processor-Memory in the IPU.

1.1. Label information

This section describes the position and content of the labels on the C600.

Both C600 and IPU device identification can be obtained from the SMBus interface when the C600 card is powered; for more details see the C600 SMBus Interface specification.

1.1.1. Card label

On the top of the C600 (visible when the C600 card is installed) is a label that repeats the PCB card identification information for your C600 card.

The command line tool gc-inventory can also be used to find the PCB serial number of a C600 card.

1.1.2. PCB card label

On the bottom of the C600 card there is a small cutout in the metal cover which shows the PCB card identification label.

Note that this label is not visible when the card is installed in a chassis.

1.1.3. Tamper proof label

On the reverse side of the card there is a tamper proof label. The lid of the C600 SHOULD NOT BE REMOVED and this label will indicate if this has occurred.

Note that this label is not visible when the card is installed in a chassis.

1.2. Physical specifications

The C600 card conforms to the PCIe CEM specification for dual-slot, full-height Gen4 PCIe cards. An additional 2.5 mm clearance is required to allow for the IPU-Link™ card-to-card assembly for systems where cards need to be connected together. A mechanical model (STP file) can be provided on request from Graphcore support.

1.2.1. Dimensions

Table 1.1 C600 dimensions

Card length	267 mm
Card height	111 mm
Assembly height	113.5 mm to top of attached IPU-Link connector
Assembly width	27.6 mm
Mass	1.27 kg

1.2.2. PCIe extender brackets

Depending on the chassis the cards will be installed in, there are different types of PCIe extender bracket available to ensure a secure fitting of the C600 into the PCIe slot. These brackets are described in Section 2.2, Extender brackets for C600 card support.

1.3. Power requirements

Power is supplied to the C600 card via a 3 V connection on the PCIe edge connector and a 12 V power supply (see Section 1.3.1, 12 V auxiliary power supply specification). The power socket is mounted on the edge of the PCB at the opposite end to the mounting bracket.

Table 1.2 C600 input power specifications

Connection	Voltage	Specified current	Specified power	Timescale
PCIe edge connector	12 V ± 8%	0 A	0 W	N/A
PCIe edge connector	3V3 ± 9%	1 A	3.3 W	20 ms
CPU8 pin power connector (AUX)	12 V +5% / -8%	16 A	192 W	20 ms

Table 1.3 C600 power management specifications

TDP	185 W
Power cap	Adjustable in multiples of 12W depending on customer spec, typically 180 W or 192 W
Power cap adjustment resolution	12 W
Power capping sample time	1 ms

Table 1.4 C600 peak input current specifications

Parameter	Peak current	Timescale
PCIe edge connector (12 V)	0 A	N/A
CPU8 pin power connector (AUX, 12 V) - default	16 A**	20 ms
CPU8 pin power connector (AUX, 12 V) - absolute max	21 A**	20 ms
CPU8 pin power connector (AUX, 12 V)	30 A	1 ms

Note

^** 20 ms averaged peak current depends upon the power cap value. For expected workloads this should be left at the default value. In cases where this is increased the chassis power capacity needs to be adjusted accordingly.

1.3.1. 12 V auxiliary power supply specification

An auxiliary power supply is required to provide the necessary power to the C600 card. Fig. 1.1 shows the pin-out diagram for the 8-pin C600 power socket.

Fig. 1.1 C600 8-pin 12 V connector pinout

Table 1.5 shows the connection summary for the C600 power socket.

Table 1.5 C600 pin connections

Pins 1 - 4	Ground
Pins 5 - 8	12 V

1.4. Thermal requirements

The C600 card is passively cooled when situated in a suitable chassis enclosure. Fans within the chassis housing the C600 card(s) need to deliver sufficient airflow to keep the cards below their maximum operational temperature threshold, removing 252 W of heat per C600 card to allow for the maximum value of power capping.

See Section 2.1, Airflow requirements for more details about airflow requirements.

1.4.1. Operating conditions

The C600 operates between 10°C (50°F) and 55°C (131°F) ambient temperature. The maximum external exhaust temperature is 70°C (158°F). Relative humidity should be kept between 5% and 90%. Power consumption is reduced if either the C600 component temperatures or the input currents exceed their maximum thresholds.

1.4.2. Storage conditions

The C600 can be safely stored between -40°C (-40°F) and 70°C (158°F). Relative humidity should be kept between 5% and 90%.

1.4.3. Temperature sensors

There are four temperature sensors on the C600 circuit board: one under the IPU device, one in the centre of the PCB and one at each end of the board, to measure inlet and outlet PCB temperature. These temperature readings are refreshed every 1 s.

The temperature readings are available on the SMBus, and through the PCIe bus for chassis fan control. See the SMBus Interface Specification document on http://smbus.org/specs/ for full details. They are also available through the PCIe bus for user visibility.

1.5. Compute

The IPU has 1,472 individual machine intelligence cores, generating up to 560 teraFLOPS of FP8 and 280 teraFLOPS of FP16 compute.

1.5.1. IPU control unit (ICU)

The ICU is powered from the 3.3 V PCIe supply. It is responsible for a number of actions on the C600 board including power sequencing, PCIe configuration, and thermal control. The ICU can communicate with the host machine via both the SMBus and the PCIe bus.

1.5.2. Cluster networking

The C600 card supports four IPU-Links with a total of 1 Tbps bi-directional bandwidth. C600 cards can be joined together into a cluster of up to eight C600 cards, with each pair of cards linked together with an IPU-Link cable carrying 2 IPU-Links. This gives a much higher IPU-IPU interconnect speed than is available through the PCIe bus alone. See Section 2.5, IPU-Link cables for more details.

1.5.3. Software support

The C600 card is programmed using the Poplar® SDK, Graphcore’s software stack for IPUs. This supports leading machine learning frameworks such as PyTorch, TensorFlow and ONNX and includes the Poplar graph programming framework which can be used to program the IPU directly using C++. Details about how to install the software required are given in Section 2.6, Installing host software.

1.6. LED indicators

The C600 card has six LED indicators which are visible through the front mounting bracket. These LEDs show diagnostic information about the current state of the card.

The IPU on the C600 has dual 8-lane Gen4 PCIe interfaces. The primary interface (primary complex) is on lanes [7:0] and the secondary interface (secondary complex) is on lanes [15:8].

LED #5 shows diagnostic information about the status of the primary PCIe interface and LED #6 shows diagnostic information about the status of the secondary PCIe interface. The primary and secondary PCIe interfaces are referred to as primary complex and secondary complex, respectively, in Table 1.6.

Fig. 1.2 C600 LED indicators

The diagnostic information available is given in Table 1.6.

Table 1.6 C600 LED diagnostic information

LED	Colour	Function
1	Green Red	Power supplies operating normally Power supply failure detected
2	None Red	All sensors operational System has detected an issue with 1 or more system sensors
3	None Red	Temperatures normal Over-temperature condition
4	None Red	System functioning correctly Critical fault
5	Green Red Blue	Primary complex (PCIe [7:0]) links functioning correctly Primary complex (PCIe [7:0]) failed to establish link connectivity Link training in progress
6	Green Red Blue	Secondary complex (PCIe [15:8]) links functioning correctly Secondary complex (PCIe [15:8]) failed to establish link connectivity Link training in progress

For any issues with your C600 card you can contact your Graphcore representative or Graphcore support.

1.6.1. Successful boot indication

During normal operation LED #1, LED #5, and LED #6 should be green.

All other LEDs should be off.

1.7. PCIe information

The PCIe information for C600 cards is given in Table 1.7.

Table 1.7 PCIe information

Item	Description
Vendor ID	0x1D95
Device ID	0x0600
Sub-Vendor ID	0x1D95
Sub-System ID	0x0102 (primary interface)

1.8. Software

C600 cards are fully supported by Graphcore’s Poplar® software development kit, a complete end-to-end software stack for developing, deploying and monitoring AI model training and inference on the Graphcore IPU. Standard ML frameworks including TensorFlow, Keras, ONNX, Halo, PaddlePaddle, Hugging Face, PyTorch and PyTorch Lightning are fully supported along with access to PopLibs through our Poplar C++ API. Note that PopLibs, PopTorch, PopART and the IPU-specific forks of TensorFlow and Keras are available as open source in the Graphcore GitHub organisation https://github.com/graphcore. PopTorch provides a simple wrapper around PyTorch programs to enable the programs to run seamlessly on IPUs. Developers can also use the PopVision™ visualisation and analysis tools to gain a deep understanding of IPU performance and utilisation - the graphical analysis enables detailed inspection of all processing activities.

In addition to Poplar and PopVision, C600 systems are enabled with software support for industry standard converged infrastructure management tools such as Docker containers, as well as orchestration with Slurm and Kubernetes.

Fig. 1.3 C600 software

Table 1.8 C600 software

C600 software
ML frameworks	TensorFlow, Keras, PyTorch, Pytorch Lightning, Hugging Face, PaddlePaddle, Halo, and ONNX
Deployment options	Bare metal (Linux), VM (HyperV), containers (Docker)
Graphcore Communication Library (GCL)	IPU-optimized communication and collective library integrated with the Poplar SDK stack
PopVision	Visualization and analysis tools

To see a full list of supported OS, VM and container options go to the Graphcore support portal https://www.graphcore.ai/support.

1.9. Main features

Feature	Specifications
PCIe interface	Dual-slot full-height PCIe Gen 4 card supporting 64 GB/s data transmission
Processor	Intelligence Processing Unit
Operating Frequency	1.5 GHz
Thermal Design Power (TDP)	185 W, maximum power 252 W
PCIe edge connector	DC 12 V and 3.3 V
Multiple C600 card support	IPU-Link cables