Recommend Asus.

Longer lifetime of laptop would depend how you using it. If you haven't use it for gaming it would last longer.

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You'd likely have to do a full board replacement, as the CPU would be soldered to the board. I've done similar with regular latitudes and some Macs (mostly to get people from 4gb to 8gb ram on their Airs, yuck) Laptops rarely have socketed cpus anymore, short of the ultra mega gaming ones, like MSI or gigabyte. More on reddit.com

Well, i've just opinions here - aside from a few lone and troublesome XPS, my company has only Precisions and Latitudes, but from that experience, I'd prefer the Latitude 5540 - especially because the chassis is the same as the Precision 3581... Reasons for the Latitude: best cooling concept of the three - which you will learn to like in longer Solid sessions - it's low-noise, and stable It has all needed ports, and actually enough of them, contrary to espacially the XPS best expandable normal barrel-type power connector, as well as USB-C PD charging. Which menas if you are working under high load and USB-C isn't enoug, you plug in a 180W PSU and you're golden. XPS are a hate point for me, to some irrationality ;-) I hate these suckers because the lousy three USB-C/TB ports as only ports, as well as the lousy cooling because of the "shiny, ultrathin" dsign. The slimmer design means there is no space for sufficient cooling airflow, which leads to rather high noise under even "middle" load due to the necessary high airflow speed even then, on the few we have, heavy throttling under load due to overtemperature So, it's simply not worth the trouble... About the inspiron. well, i stay away from them because the inspiron line is Dell's "basic consumer" line, and, to put it mildly, is likeliest to show quallity issues. The 2-in-1 may not have the braindead hinge design of the normal Inspirons, but i've seen to many posts about them here, too, for my taste. In the end, Latitude is the "Business Workhorse" line, and in many details, it shows... More on reddit.com

I recommend either the Dell Latitude or Precision lines. More on reddit.com