If you're new to building computers, one of the first little pieces of trivia you'll probably come across is that AMD CPU used pins on the bottom, while Intel ones use little contact pads with the pins on the motherboard's socket instead.
But why were these choices made? Do the engineers at AMD just think that pins are prettier? Well, it turns out that the use of pins versus pads is a very deliberate design choice. You see, Intel's approach of having pins on the mother board instead of the chip, called a land grid array or LGA, typically makes it easier to fit more contacts into a smaller space on the CPU. Modern CPU need a lot of contacts for their high speed features and to promote stable power delivery by spreading out the current.
The other thought is that because tiny pins are very fragile, you know, because they're super thin. Well, it would be better to place those on the mother board rather than the CPU, because it's not uncommon to see ah, $400 CPU installed on a $150 mother board. So if one of those things was going to break. You'd rather it to be the cheaper one, right? Then you can reuse that CPU on a new mother board. Of course, you can still mess up in LGA processor by touching the gold contacts on the bottom with your oily little fingers. But overall they are harder to damage then pin grid array or PGA chips. PGA chips, are the ones with pins on their undersides and compatible motherboards, for those have corresponding holes on their sockets. You can probably figure out that this makes PGA chips are little bit easier to damage. However, there are some upsides to using this design over a land grid array. For one, the pins on PGA chips are a little tougher than the mother board pins that you'd see in an LGA socket, meaning that they are easier to repair in the event that they do get bent, which I'm sure you can sympathize with. If you have ever had the misfortune of having to re bend even just one damaged pin on LGA mother board. The superior durability of PGA pins means that they continuously handle a little more current than LGA packages, which can be important, depending on how the chip itself is designed.
For another advantage that you can more readily experience firsthand when building or upgrading your own PC, PGA chips tend to be a bit easier to install, since there are no super delicate mother board pins to worry about, though of course, you do have to make sure that you hit every hole in the socket properly.
These advantages have led AMD to keep using PGA for its consumer level chips even long after Intel abandoned pins on their desktop chips way back in 2004. And even though current third Gen Ryzen processors actually have more contacts on the bottom than their Intel iCores, and he still found a way to fit all those pins onto one package, partly because the processes themselves are physically larger.
As you might have figured out, LGA does allow you to cram more contacts per unit of area, so they're actually are AMD chips that do use it. They're Threadripper lineup for high-end desktop PCs and their epic lineup for servers are both based on land good array designs with over 4000 pins. So if you're lucky enough to be using one of those monsters, definitely don't bend any of those delicate mother board contacts.
As far as what all this means for you, the consumer, though. Well, nothing, because you shouldn't be choosing a CPU based on whether it's PGA or LGA. It doesn't really affect performance in the way that the architectural design or the clock speeds of the core accounts of the chips do. And the reason that Intel and AMD went their separate ways. It's just because they valued different aspects of these designs, since each one does have their pros and cons. It's just important to be aware of the pitfalls whenever you're installing either of them so you don't mess up the bottom of your chip unless you want a very expensive coaster for your shot glass.