PCIe* Add-in Card and PSU Power Budgets

Three dominant power demands dictate the total system power provisioning:

1. CPU power consumption
2. PCIe Add-in Card power level
3. Rest-of-Platform power demand

Rest-of-Platform (ROP) collectively includes anything in a system (memory, storage, motherboard, peripherals, etc.) not including the PCIe Add-in Cards or CPU. Table 3-2 provides examples that generally balance these three power demands to obtain an overall PSU power rating. The PCIe power entries in the table are standard power levels for PCIe Add-in Cards defined in the PCIe CEM 5.1 Specification. As a consequence of the introduction of 450 W and 600 W Card power levels, the wide range of possible PCIe card power demands plays a dominant role in setting total platform power supply ratings.

These configurations will also serve as test cases for evaluating power supply excursions. The peak power demands of the PCIe Add-in Cards at each power level can guide the peak power demands of the PSU.

In cases where a PCIe Add-in Card has a sustained power not listed, use these values as a minimum value for all cards up to these power levels. The table below should be considered as a minimum power level based on Rest of Platform (ROP) power. The ROP assumptions are shown in Table 3-2 below. If a system designer plans more ROP power, the overall platform power budget for a system must be increased. If a system designer plans less ROP power, then the PSU size can also decrease. In the case of ROP values lower than what is shown in Table 3-2, the calculations should be done for Peak Power Requirement for this specific system. If the Peak Power requirements for this specific system exceed the values shown in Table 3-3 then a PSU with support for higher peak power levels would be needed.

The CPU continuous power comes from Section , taking the current value and multiplying by 11.2 Volts to create a power value and round up slightly. The CPUs used in these examples are the 65W TDP for the first row and 125W TDP for all other rows.

Table 3-2: PCIe* AIC and PSU Power Budget used for Peak Power Excursion Test Cases

• Rest of Platform power here will not apply to all systems.
  • If Rest of Platform power is higher than what is in the table, increase the PSU size respectively.
  • If Rest of Platform power is lower than what is listed in the table the PSU size can also be reduced, but Peak Power requirements might then go beyond what is listed in Table 3-3. The table above represents a balance between ROP and Peak Power Excursions.
• CPU Power and Rest of Platform Power can vary from this table which would result in custom Peak Power requirements.