Thanks!
Justin C.

Sure, there will be diminishing returns, but as with all these mobile parts, in this case with the i5-1235U and the i7-1265U there, will still be a significant performance difference–at the very same TDP or heat point.

The difference between the two is no longer just Intel cutting certain fuses to provide a spread for every niche in the market (not that that’s gone away completely). At least part of it is really just binning and that’s really rather analog these days and not just about transistors working or not or chips failing to function beyond a certain speed.

While that can obviously happen, binning is mostly about the quality and impedance of wire-transistor interconnects and how they’ll require a bit more voltage (or not) to push signals at a given frequency. And of course, higher voltages imply higher power consumption, which also has chips failing eventually, but it’s the power budget that seems to be the more significant hurdle for binning.

E.g. in Skylake/Kaby-Lake times hyperthreading wasn’t cut for some bins because some transistors weren’t working, but mostly because it helped keeping the power budget in check. Real chip defects on the other hands could “crater” cache SRAM banks or full cores, so these i3-1215U could really be that type of salvaged chips—or require 30 Watts to run with fully enabled cores: too high to sell in a mobile space for 2P performance.

A lot of these i5-1235 might have no issue reaching “i7-1265 frequencies” or in fact higher yet, but they’d get hotter in comparison and at a certain point too hot for the platform constraints.

So on a mobile platform, those i7 will generally get you more overall compute out of the same battery power as well as a bit more peak, while on a passive heat constrained platform it’s more about the level and the length at which peak and sustained performance can be maintained.

Paying more for the i7 will almost certainly give you more performance in one way or another, than what you can get on the i5. Whether that those additional Hertz justify the extra $$$ is mostly a personal question, not technical.

I tend to re-purpose hardware; few systems ever get to serve out their life-time in the very use case for which they were bought. So, for me to aim a little higher on the parts isn’t a guaranteed waste, but often an opportunity to remain usable on a new job. It obviously doesn’t mean I’ll always aim for the top spot, either, or only when prices have stopped being crazy.

The most extreme examples of how far binning could spread from my past personal experience where Yorkfield/Harpertowns Quad-Cores, which Intel made around 2007/8 in a shrink of the 65nm designs to 45nm. Early Q9550 (2.83GHz) didn’t actually do much better than their Q6600 65nm (2.66GHz) predecessors, both balked at being pushed to the then magic 3 GHz, mine got hot and failed very quickly, others were luckier.

I had plenty of these for my kids so when I was hunting for a cheap way to extend the platform’s life-time I found Xeon X5492 being sold off for a pittance as well as ways to have LGA 771 chips fit into an LGA 775 socket (+ BIOS patches to make them work).

These Xeons were the truly golden sample Harpertowns/Yorkfield chips, the very best bin ever made on that 45nm process and even proclaimed that on their CPUID. While their official rating was 150 Watts of TDP, quite a lot for that socket at the time, they never came near that power consumption. Instead, they ran a very cool 50 Watts on Prime95 loads and reached 3.4 GHz and 1.6GHz FSB without breaking even a sweat on a box cooler.

They were mostly identical to the Core 2 Extreme QX9775, which officially only ran at 3.2 GHz also with 150 Watts of TDP, but that had an unlocked multiplier allowing them to complete Prime95 at 4GHz with some overclockers out there.

The gap between my first Q9550 which refused to do 3 GHz and those golden samples was more than 40%, which is why the industry then went into Turbo mode and monetized those bins to the utmost.