https://benzhaomin.github.io/bdiefinder/
since you have ddr4, use the b-die finder. ddr4 availability isn't great, so i would try to find a 4000cl16, or 3600cl14-16. this is a good 32gb set for the money. ddr4 is a good deal more expensive than ddr5 now unfortunately, that kit is by far the cheapest fast 32gb kit i can find. if you want to go with only 16gb though kits are easier to find.
14700k @ 265w load in cinebench r23 never breaks 90c and never throttles. this is with a phantom spirit and a contact frame. harder to cool than a 13700k too because of the extra e-cores.
you don't need an aio. seriously, save your money. on my 14700k (harder to cool than a 13700k because of 4 extra e cores), i am under 90c all core load running cinebench r23 with a thermalright phantom spirit 120 and a contact frame. that's with a 265w load. you'll never see those numbers in a game either.
upgrade now, the 13600kf is a great cpu. a 2500k is fine for web browsing (my parents pc has my old 2600k) but beyond that it is very slow. pc recycling centers junk anything older than 4th or 5th gen these days, so if you tried to donate it, it would literally get thrown into the trash. next gen will not make a huge difference, maybe 10% or so, and you'd have to suffer for another year with 2nd gen. there is no reason to wait with hardware as slow as yours. ddr5 is also very very cheap now, so it's a good time to buy. if you have a microcenter near you, even better, since you can probably get a mobo/cpu/ram for $350-400.
upgrade now, the 13600kf is a great cpu. a 2500k is fine for web browsing (my parents pc has my old 2600k) but beyond that it is very slow. pc recycling centers junk anything older than 4th or 5th gen these days, so if you tried to donate it, it would literally get thrown into the trash. next gen will not make a huge difference, maybe 10% or so, and you'd have to suffer for another year with 2nd gen. there is no reason to wait with hardware as slow as yours. ddr5 is also very very cheap now, so it's a good time to buy. if you have a microcenter near you, even better, since you can probably get a mobo/cpu/ram for $350-400.
it's $10. it will lower your temps by 8-10c. it takes five minutes to install. i don't get why it's such a contentious issue, people spend $200 on AIOs that do the same job as a $40 dual tower heatsink, but can't be bothered to buy a little metal frame for $10 that will make more difference than either.