not sur I understand the thing about 2 cores, still need all the cores possible; but yeah I figured the 4 thunderbolts model also has 2 fans.
"2 cores" worth of work covers lots of workloads. For folks who have some deep need to engage 4 cores with constant work for double digit minutes ( or hours ) at a time on "wall socket" power , then the 2 fan model would be incrementally better. However, for many mixed loads and run primarily on battery the 1.4GHz model is probably better (if primarily need a mobile laptop and not a periodically mobile desktop which sits in one/two locations about every day. ) .
About the TDP, I don't understand if it's a logic limitation backed into the processor; or just a guideline for manufacturers to scale their cooling system?
TDP is Thermal Design Power. It is Thermal mark the system should be designed for. Usually there is a group of CPUs/GPUs that have the same TDP ( more larger group in typical CPU product SKU groupings). Those can all use the same coolers. Where the cooling system is primarily integrated into the system, it isn't just the "cooling subsystem". It is also not just cooling as source power is coupled to that also ( bigger TDP probably means you need a bigger power supply also. Which has impact on system design. ).
Why does Intel use the same chip die to deliver two different product TDP grouping SKU , because coming up with the base design for a die costs many, many millions of dollars.
[ aside: most of the "MBP thermal throlling" rants are about the MBP cases not handling the Intel CPU that are grossly going over their TDP ratings. It isn't that Apple has designed under those, just not out to the max that the CPU can ask for with the default Intel firmware setting..... which is higher than Intel docs state. It is on Apple to cap that to something closer to the spec if that is what they designed to. ]
That said the TDP is more so a normal operating range guidance. Many of Intel's 6-8 core CPU models these day blow way past their "rated" TDP limit. For the context of these two MBP 13" models the i7's are probably closer to be violators than the i5 options. However, probably not in huge deviations with these 4 core models.
wouldn't this 1.4 Ghz processor perform exactly the same as the 2.4 Ghz with the same cooling system?
Overall? No. Because the chips have self limiting features that can be set. The "max clock" is a setting. If set to 1.4GHz the cooling system can huff and puff and hard as it can.... the CPU won't clock any faster that what the "max clock" setting says. [ You may be confusing with "unlocked' CPUs where the end user can 'plug-in' any 'max clock" setting they want to. Those aren't sold in the mobile space, because typically in vast majority of mobile enclosures that is a bad idea. ]
Workloads which invoked Turbo ( mostly single core with just some dual core ) there are some cases where the 1.4 might do incrementally better if it had the 4 port cooler. However, once you engage all four core for extended time workloads there would be a gap. The 2.4 probably isn' going to generate so much heat that it will underclock itself down to 1.4GHz. ( presuming were not impeding the enclosure somehow: high ambient temp , blocking vents , or interfering with cooling from the case bottom. )
