3 ms·
The difference between input power and thermal output of a CPU is negligible. A tiny amount of electricity is used for external signalling, the rest gets conver
by magila 8y ago
The difference between input power and thermal output of a CPU is negligible. A tiny amount of electricity is used for external signalling, the rest gets converted to heat. So in practice TDP can be treated as a limit on input power. In fact that's exactly what Intel CPUs do by setting PL1 equal to TDP by default.
- ajross 8y agoNegligible over time. What has everyone inexplicably confused is that electrical draw is allowed to be higher instantaneously than the output cooling will allow to accommodate bursts of computation. And some how everyone thinks that's a bad thing. Again, TDP means the same thing now that it did 15 years ago.
- toast0 8y agoWhat you've described is how it used to be, maybe you gets few seconds of usage over the TDP, but then the processor throttles back to hit the spec. That can still happen (and often does in laptops etc), but as described in the article, and many others, many to most motherboards sold as individual components are configuring the chips so that they will run at a higher power state for an indefinite time, so long as the temperatures stay within operating limits. It would be nice to know what the expected power input / heat output is in that state, so you can get cooling to match, and have it in turbo mode at all times when the CPU is being stressed. Cooling to the TDP only will (or should) get you the base clocks and a brief amount of turbo, but is likely to thermal throttle quickly. This also brings more into question the adequeacy or not of the thermal interface material used between the CPU die and the heatspreader -- if the CPU will run turbo for longer if you keep it cooler, there's more frustration about less heat efficient solutions.