Advanced Micro Devices Inc (AMD)

[wbmw]

Re: you say that the document does not say the Opteron will dissipate this power (the shown TDP) if the core temperature reaches that high.

There is a relationship between power and temperature, but it's not the TDP. If you follow the math equation I discussed in my last post, you'll see it's nothing more than the column row, subtracted by the ambient temperature, and then divided by the thermal resistance. This is a term describing how much the processor is currently dissipating, if you measure the temperature at the value indicated by the table row, assuming you are using the thermal solution with indicated thermal resistance and an ambient temperature listed in the table.

In other words, if you measure a thermal profile 'B' CPU with 0.27C/W thermal solution at 59C degrees (and ambient temp of 42C degrees), then the processor is dissipating 63W of power. If you then run an application that causes the processor to dissipate 85W of power, you can expect the temperature to rise to 65C degrees. Can you see the relationship, now?

Re: So please explain to me where I am wrong in thinking the documents shows the applicable TDP based on the variable TCase max for a given thermal profile?

You seem to think that at a given temperature, the power listed is the max that the processor can dissipate (i.e. the TDP). It's actually the current power, if you measure the processor at that temperature. Another example: if you have a processor with thermal profile 'F' and measured temperature of 57C degrees, then the current processor dissipation is 68W. If the processor starts running new code and falls to 44W, the cooling solution would eventually cool the processor to 53C degrees.

Obviously, if you used a stronger cooling solution than the recommended 0.25C/W, the temperature at 44W would be lower. The tables are not comprehensive, but you can estimate the temperature at 44W for a 0.20C/W cooling solution by looking at thermal profile 'I'. 44W with that cooling solution is only ~51C degrees (6C degrees less than profile 'F').