ATX12VO (12V Only) Desktop Power Supply
Design Guide
Processor Configurations - RECOMMENDED
The processor power in a desktop computer is provided by the 12V2 power rail of power supplies with multiple power rails. To meet the desktop processor power needs, a desktop power supply must provide the current value listed in Table 2-1 for the 12V2 voltage rail. Table 2-1 shows the various processor current requirements represented by the desktop processor’s TDP. If a power supply only has one 12V rail, then Table 2-1 shows the amount of current that needs to be dedicated to the desktop processor in a system level power budget.
Table 2-1: 12V2 Current for Processor Configurations
PSU 12V2 Capability Recommendations | ||
Processor TDP | Continuous Current | Peak Current |
150 W | 33 A | 60 A |
125 W | 26 A | 39 A |
65 W | 23 A | 34 A |
35 W | 11 A | 19 A |
- If the power supply supports the 240 VA Energy Hazard protection requirement, then current levels for the 12 Volt rail above 18 Amps must be divided into multiple 12V rails.
- Continuous current is defined for the processors PL2 (Turbo) power limit since desktop processors are expected to stay at PL2 for many seconds, sometimes close to 1 minute. For a PSU, any time over 1 second is considered Continuous current.
- Peak Current is defined for the processor’s PL4 which defines Peak current for a max time of 10 ms.
All future processor power/PSU current requirements will be defined in a document titled ATX12VO and ATX12V PSU Design Guide Addendum (#621484) that is applicable to both Single Rail and Multi Rail ATX Power Supplies. Refer to that document for details of where these values come from.