Which is hotter (in temperature): i5 or i7? - 8th gen, both 15W

Question

I'm specifically interested in the i5-8250U vs its alternative, the i7-8550U. I've seen this review about a Thinkpad that has been tested thoroughly with the i5-8250U processor. But right now where I live I have a flash sale where I can purchase it with the option to get the i7 for just 30€ more.

Its just a 10% faster but being just 30€ more I could pay for the update. Yet, noise and heat are primordial for me. Noise seems to depend on several factors, and too difficult to figurate out unless you have experience with it or can just compare them side by side, so I'm focusing here on the heat: is an i7 (this one in particular at least) hotter (or cooler!) under the same taskload and same hardware?

Both have a thermal design power of 15 W. In the pic below you can see the only two differences between them in red:

The same web compares its Power Consumption:

Which makes me think the i7 would be hotter but really don't know what those tests really test..

Can you give some insight/clarification/answer/idea/s?

Solution

I don't think there will be a large difference. Theoretically, if the TDPs are the same, under 100% utilization, both should generate same amount of heat.

However, like confetti said, for same task, the average utilization of i7 would be lower since it has better performance. At my best guess, if the heat rate is fully proportional to utilization, i7 will be cooler in this case.

Comments

[confetti]

More power means more heat. The i7 will definitely get hotter under load but there should be a sufficient cooling system in the laptop.

[Martin]

so you mean, "it will definitely get hotter under SAME load? Cause I could think of the more powerful processor trying to do more things or doing them faster and becoming hotter because of that... And if it does them faster it will be hotter but for a briefer time - then it could even be cooler once the task is finished...

[confetti]

It's hard to say that because the i7 will run faster and therefore hotter under same load. But it will get the processing done faster, so it will be more heat but for less time. If the CPU supports it you could underclock it, that would reduce heat by a LOT.

[Martin]

Thanks @confetti, but my aim is touching the defaults as less as possible; it is an office laptop, and I just want to compare the two to know which one is cooler and buying it (I guess I can reduce the heat in both but I'd rather reduce the heat of the already cooler one)...

[Ramhound]

I meant the model of the laptop. Anyways I missed the link. I will just delete my comment since you are treating me poorly

[Martin]

@Ramhound ?? What of what I've said could have offended anyone? And why have you deleted your comments? They could have added to the discussion...

[Ramhound]

You made it clear you didn’t consider them to be helpful. The fact they were a discussion is the exact reason I deleted them.

[Martin]

I didn't say that. Those messages could have been useful for others, and at least they would have avoid others saying the same if they wanted to help me too. those together with the questions I made to you would have helped clarifying the discussion. But as you please, it's ok for me and maybe this is more a sort of meta discussion ... Be happy! :)

[Martin]

That was my hypothesis, but then how do you explain the second pic? It doesn't seem to support it...

[Zhongjie Shen]

If you click on the '+' button, you will see it might be the consumption of the entire system, not just the CPU. These higher end i7 laptops have more powerful graphics etc. push the power consumption higher.

[Martin]

I see, so the difference is just due to the laptops... Thanks! :)

[Martin]

I kept researching and found this: the Core i7-8550U, ... performs about the same as the Core i5-8250U. ... the Core i7 under continuous load is actually slower than the [i5] ... Lenovo has set the TDP to the max for this CPU class at 44 watts... – but temperature rises rapidly, making it reduce its clock speed after just a few seconds... The Core i5-8250U on the other hand performs better under continuous load, since its power consumption maxes out at 30 watts ... Thus the temperature of the cheaper processor model stays lower and its performance higher.

[Martin]

From notebookcheck.net/…. in case anyone is interested...