Intel Processor Suffixes

U-series

U means “ultra-low-power,” and that’s basically it—they’re chips that aren’t necessarily the very best in terms of CPU performance, but they’re instead low-power designs made with efficiency in mind. They have lower clock speeds, lesser cores, and more importantly, a very low TDP. The Intel Core i5-1265U is rated for 15W, and can turbo up to 55W in brief bursts. Some U chips go as low as 9W. These chips can be cooled relatively easily, and depending on the PC’s design, they could even be cooled passively.

https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus

P-series

P chips sip a little more power—28W, to be precise. That’s almost twice (or even triple!) what a U-series chip requires. As such, power and thermal requirements for these chips are higher, and you’ll need beefier cooling. But at this point, it’s nothing that would make a thin and light laptop thicker than it should be, and with the right cooling, it shouldn’t be a problem.

https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus

H-series

Unlike the P-line and U-line, the H-lineup is not made to fit into a thin, lightweight laptop. While those chips go up to 28W, an H CPU can go up to a whopping 45W. Granted, that’s not even close to a desktop CPU (the Core i9-12900K sips 125W), but for a laptop, that’s actually a lot—remember, they have enclosed, tightly-fitted spaces where internal components don’t have a lot of room to breathe. That doesn’t mean they’re not good. In fact, they’re pretty much as good as it gets for laptops.

https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus