[SOLVED] Confused about Intel's ATX v3.0 PSU Standard Guide

[Everest2099]

Intel released "ATX Version 3.0 Multi Rail Desktop Platform Power Supply" design guide recently. There are 2 things confuse me.


1. A 65W TDP CPU requires 275W of power

According to the guide, a 65W TDP CPU draws 23A of continuous current. Multiply this value by 11.2 Volts to create a power value and round up slightly, a 65W TDP CPU requires 275W of power. It really confused me. Does anyone have any ideas? Does a 65W TDP CPU really need 275W?


2. Graphics card over 300W might cause unexpected card or system malfunctions

According to the statement, graphics card over 300W might cause unexpected card or system malfunctions because PCIe 4.0 is limited to 300W. Does this mean that cards over 300W, such as RTX 3080 and RTX 3090, should be used on the PCIe 5.0 interface, though PCIe 5.0 wasn't even on the market when they were released? Or did I misunderstand something?


The Full guide can be downloaded from here.

 

[4745454b]

They will run on PCI3.0 or 4.0, but you need to make sure you have a PSU that can handle the momentary load that goes above 300W. The PCIe 5 spec, and I understand it, is bringing a new 12pin plug to allow cards to officially exceed the old 300W limit. You'll be fine running on the old standard or the cards wouldn't have come out. You just need to make sure you have a PSU that can handle it.

 

[DRagor]

a 65W TDP CPU requires 275W of power. It really confused me. Does anyone have any ideas? Does a 65W TDP CPU really need 275W?

Why it confuses you? i7-12700 is a CPU that is TDP 65W - and can easily draw above 200 W. Those numbers seem perfectly fine to me.

 

[4745454b]

If you are wondering why the numbers are so far apart, I'll attempt an explanation. TDP != power draw. Or =/= for other languages. They are normally related as you can't generate heat from nothing. The reason why 200W exists is because the CPU can draw on a temp basis much more power than the Thermal Design Power allows. The TDP is a rating the cooler manufacturers need to know. How much heat energy is coming off the CPU. But it won't be constantly drawing 65W no matter what. It can idle down into the low double digits, and yes, temp draw much above that. On avg during a load it will put out ~65W of heat energy, but the PSU needs to be able to handle the peak loads. Which can be 3x+ the TDP.