What is this chip measurement called?

[willfr]

Forgive me if this question is just wrong, I'm just curious and was hoping someone could help explain.

With the performance of so many devices (smartphones and tablets) largely being dictated/bottlenecked by its thermal capacity (the larger the device, the more heat it can handle), manufacturers want to go with a chip that has the best "performance per heat-output" ratio, so they can get the most performance out of their device design. This measurement is the true measurement of performance for these chips, but what is it actually called? (I highly doubt it's called "performance per heat-output ratio" hahaha). Also, obviously the manufacturing node of the chip plays a big part in this measurement but doesn't the microarchitecture also play a big roll? Ideally chip companies would design with this measurement in mind because it's the true dictator of performance.
I wish there was an industry standard for this measurement and chip companies would advertise it when they announce new chips 🙁 In my opinion, it's just as important and relevant as performance per watt or performance per dollar

 

[PeterScott]

Performance per watt. The term is mentioned a lot.

Though there is no general numbers. It would be VERY workload specific.

 

[maddie]

Watts measure energy generation [J/s] which can be related to heat. In silicon circuits, wattage always ends as heat output, baring a very tiny amount in some cases [eg: EM fields].

 

[willfr]

In silicon circuits, wattage always ends as heat output, baring a very tiny amount in some cases [eg: EM fields].

Ah I didn't know that, thank you! But surely they also directly measure the heat output of chips? What are those measurements known as?

 

[PeterScott]

Ah I didn't know that, thank you! But surely they also directly measure the heat output of chips? What are those measurements known as?

No it isn't measured. Because you would have to isolate it completely and capture every BTU, and if you did it accurately, once it was all said and done. Watts consumed would equal Watts of heat produced.

For all intents and purposes, the two are interchangeable. Nothing is gained by attempting to measure all the heat produced unless you are doing experiments verifying first principles physics.

Generally speaking there are TDP (Thermal Design Power) numbers for chips to give an idea of the kind of cooling system you need to provide.

But those are just ballparks, and in usage chips regularly exceed that. But if you are actually using part in mobile or somewhere with a limited cooling solution, the chips can actually be configured for different wattages that they won't exceed (Say 15 watts), and then your cooling limited cooling system can be designed to cool that load and all is well.