Well first thing you should find out before anything is if your laptops is REALLY dead. I find that 9/10 laptops that die aren’t actually dead. First common issue is the high heat killed your main battery. And as odd as it is, the laptop may still work if the battery is removed and laptop plugged in. (If you have a battery that is removable and you use your laptop as a desktop, always remove the battery as heat kills lion batteries. A cooler is also a good investment to protecting your laptop battery)
The other common issue is the CR2032 bios coin cell battery died that powers your bios. Sometimes, it isn’t even dead and you just gotta take it out, let it discharge a bit and put it back in.
If it is really dead, depending on what kind of ram you have inside it, you can salvage that and if it is DDR4 you can still use that on modern laptops. Personally, one of the best computer investments to make is getting a good deal on some ram and buying it separately. I bought 2 ram sticks for total of 64gb ram separately for about $180 a few years back. Getting that from a manufacturer would cost $300-500+. And when I got my next computer, I just moved them over. Pretty much a 1 grand savings right there. Of course this only works if you are buying within a generation, with DDR5 around the corner it probably isn’t the best time. But it is a good thing to know when buying laptops. Of course it kind of limits you to options these days as vendors started soldering ram
Ah, no. Technically, U would generate less heat than HQ as more power means more heat. That said, it is relative. Most U notebooks come with poor cooling as they aim to be lighter. And technically speaking a more powerful processor can finish a task faster so it can idle more. I would check out the website called notebookcheck.net , they have very good reviews of laptops from power to heat levels to benchmarks to display color accuracy.
The real difference between i3, i5, i7 and i9 is hyperthreading and turbo boost. Of course sometimes the upper models will have more cores. But end of the day, most of that means squat. An i3 can outperform an i7 depending. I mean do understand there is something called thermal throttling. Which means if your laptop gets hot enough, the performance will drop. This is why with the poor cooling systems of many laptops out there, most of it is just marketing gimmicks. And the only true way to know how good a laptop performs is to find places that do benchmarks. It is now even worse cause many CPUs have multiple Wattage profiles despite having the same name.