[SOLVED] Power supply max current for CPU?

Apr 30, 2021
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I do not fully understand the max current for the CPU and PSU and how they work together...

Ryzen 9, for example, has EDC of 140A and TDC of 95A. But my PSU is Antec HCG650 GOLD and it is specs claims that the max current of the PSU is 54A...

But 54A is much lower than 140A even 95A. So, how does the power supply actually supply the CPU current requirements?
 

popatim

Titan
Moderator
You need to take the voltage into consideration.
100a @ 1v could be supplied by 1a @ 100v if the conversion efficiency could ever be 100%.

In the case of CPU power, the PSU supplies 12v via the EPS connector (the 4+4) so 12v x54A= 648watts that it could deliver. (Is that 54A peak or continuous?)

In your Ryzen examples, I'm guessing your figures should actually be Watts and not Amps.
The AM4 socket has a limit of 142w... And the motherboard would break that 12v supply from the EPS down to several different lower voltage rails to feed to the CPU. The EPS 8pin (4+4) has a max rating of 336w. (28A @12v)
 
Apr 30, 2021
36
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30
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In your Ryzen examples, I'm guessing your figures should actually be Watts and not Amps.
No, the EDC and TDC are in Amps. For example (top right):



So, if I understand you correctly, the CPU EPS connector can supply 12V x 54A (=648W) but the CPU itself can use that as max power but changing the voltage / amp as it wants? For example, reduce the voltage to 1V in each core but raise the current to 140A for EDC, so the total power for EDC lines is 140W? Without actually take 140A from the power supply?
 

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