Why are Noctua's TDP ratings different for AMD and Intel?

[corrado33]

Take a look at Noctua's TDP ratings.

 

http://noctua.at/en/tdp-guide

 

Seems odd that the rating for 1151 for certain coolers is around 95W, but then for the same cooler and for AMD sockets, it's 220W? I mean, the physical size of the chip can't make THAT much of a difference...

[Veninblazer]

Look at the FX-9590's TDP

[corrado33]

1 minute ago, MasontheDeathbat said:

Look at the FX-9590's TDP

That doesn't make any sense. It's a heatsink. It doesn't care how the heat gets to it. It either CAN or CAN NOT dissipate that much heat. So if it can dissipate 200W from AMD, why not from Intel?

[JefferyD90]

13 minutes ago, corrado33 said:

Take a look at Noctua's TDP ratings.

 

http://noctua.at/en/tdp-guide

 

Seems odd that the rating for 1151 for certain coolers is around 95W, but then for the same cooler and for AMD sockets, it's 220W? I mean, the physical size of the chip can't make THAT much of a difference...

AMD and Intel do not rate their CPUs based on the same TDP methodology.  There is no industry standard for this that companies go by.  Its one of the biggest marketing schemes in the history of CPUs.

[corrado33]

Just now, JefferyD90 said:

AMD and Intel do not rate their CPUs based on the same TDP methodology.  There is no industry standard for this that companies go by.  Its one of the biggest marketing schemes in the history of CPUs.

That was what I was going to guess. But that also doesn't make sense. A W of power dissipated is a W of power dissipated... Should it not be easy to measure how much power a CPU dissipates? Heck, I could do it...

[JefferyD90]

1 minute ago, corrado33 said:

That was what I was going to guess. But that also doesn't make sense. A W of power dissipated is a W of power dissipated... Should it not be easy to measure how much power a CPU dissipates? Heck, I could do it...

Intel measures it as a TDP over the whole chip while AMD measures it at the core.  Its legitimately a different method.  Honestly, AMD chips and Intel chips have been MUCH closer than anyone imagines for the past few years.

[SCHISCHKA]

i want to throw in here that they have different chip packages. one is soldered one is filled with goo. so an AMD may have a higher TDP at its core but it is able to transfer this heat to the cooler better

[oriol]

44 minutes ago, corrado33 said:

That doesn't make any sense. It's a heatsink. It doesn't care how the heat gets to it. It either CAN or CAN NOT dissipate that much heat. So if it can dissipate 200W from AMD, why not from Intel?

There are huge differences. For example, AMD specifies a maximum temperature of only 65°C whereas Intel CPUs can stand 95°C. Keeping a 100W CPU below 65°C is a completely different thing than keeping it below 95°C.

 

As for the 95W vs. 220W rating, there are two things to note. Firstly, they state "The indicated W value refers to the maximum recommended Thermal Design Power (TDP) as specified by the CPU manufacturer.", so if it says 95W at Intel, this is because the highest rating given by Intel for LGA1151 CPUs is 95W. Secondly, note that the coolers that are rated at 220W AMD are rated at " 95W & OC***" for LGA1151, so this means "*** = best overclocking potential" on a 95W CPU. So obviously a cooler like the NH-D15 can do more than 95W on Intel.

 

As for why they don't just specify a maximum wattage, just read the opening paragraph: "Noctua does not specify the performance of its heatsinks in terms of maximum possible heat dissipation because the question of how much Watt (W) a heatsink can dissipate depends on various parameters such as the type and shape of the heat source, contact quality, contact pressure, thermal interface material application, ambient temperature, etc. As a result, the maximum possible heat dissipation value varies from platform to platform and between individual systems."

[Deli]

Think about GPU. Many top end GPUs have a 250W+ TDP. I don't think the air coolers on those cards are any bigger than say, a DH15.

 

So, the TDP rating of a cooler shouldn't be taken literally.

[corrado33]

15 hours ago, oriol said:

As for why they don't just specify a maximum wattage, just read the opening paragraph: "Noctua does not specify the performance of its heatsinks in terms of maximum possible heat dissipation because the question of how much Watt (W) a heatsink can dissipate depends on various parameters such as the type and shape of the heat source, contact quality, contact pressure, thermal interface material application, ambient temperature, etc. As a result, the maximum possible heat dissipation value varies from platform to platform and between individual systems."

Well obviously yes, but there are things called "standards" for a reason. It would be seriously easy to use the INCLUDED thermal compound, applied optimally or as noctua specifies, then keep the room at 20C (standard temp) and specify "standard TDP." This is extremely common throughout... well... everything. Why not here?

[oriol]

I'm not aware of any common industry standard for this, on the contrary. I just see some brands boasting absurdly high TDP ratings without specifying how they measure. It seems to me that Noctua just doesn't want to take part in this dubious "TDP race" or try to establish a standard that may make their coolers appear worse than the competition because it would be based on measurements rather than marketing.