The AM4 platform is getting a little long in the tooth these days, to say the least, but AMD has continued supporting it long after we probably had any right to expect them to. One reason for that is that modern motherboards have gotten crazy in terms of price - it used to be that a "good" motherboard would run you maybe $100, but now to get anything decent you really need to spend *at least* three times that, and then you'll need a new CPU and RAM on top of that. So AM4 has remained popular even with AM5 having been on the market for several years now, and AMD has continued producing processors for it. Many of us are just resistant to spending a large amount of money on a new motherboard when there's no real reason we should have to, and honestly no real reason they should cost that much to begin with.I've been rocking the same motherboard for about 7 years now (an MSI B350 PC Mate), and luckily it's been updated over the years to accept both modern CPU's like this one (yes, that means Ryzen 9's too, which the B350 chipset did not originally support) as well as faster RAM, so I have no need to upgrade to the AM5 or equivalent Intel platform just yet. A used PC Mate or Tomahawk (the gaming version of this same board) would not be a bad investment if you're on a budget and new to AM4! One caveat is that updates on older AM4 boards to support newer CPU's have to be done on older CPU's that they already support - a CPU like this one just won't work at all on a non-updated or older AM4 board. Ask me how I know. (I had to reinstall my old CPU to update my motherboard, then install the Ryzen 9 a second time.)So if you're upgrading from an older CPU, make sure you check for your motherboard's CPU compatibility and update as necessary *before* installing this processor. If you're on a budget and buying from scratch into this platform - and that's still not a bad idea, since price/performance ratios on AM4 are very good these days - make sure you get a motherboard that's either already been updated to support this processor, or did from the start, because you won't be able to update your board without a CPU it supports already in it.The Ryzen 9 5900X is among the fastest CPU's you can get for the AM4 platform. The 5950X is slightly faster but you get diminishing returns for the price. The Ryzen 7 5800X3D is better for gaming, if that's all you want to do, but it's significantly slower for things like content creation or anything requiring basic floating point or integer calculations.I chose the Ryzen 9 5900X as most likely the last AM4 CPU I'll ever buy because it was at that sweet spot in price where I could justify an upgrade over my old Ryzen 7 3700X, and I do a lot of different things with my PC - not *just* gaming. You can see that in the Passmark results I've posted, the CPU is in the 93rd percentile. That's not bad for a $300 processor on an 8 year old platform.These processors do take to overclocking pretty well too, although I've had limited results with that on my old motherboard. I do think the B350 chipset is a bit of a limiting factor there - remember, this chipset originally didn't support the Ryzen 9 family at all. Multi-threaded performance on my machine is a little bit below average relative to others with this same CPU even after using AMD's Ryzen Master utility to try to wean as much as I can out of this chip. So your mileage may vary and on an X370-based motherboard, or just something newer than mine, you could probably do even better.You're going to need a cooler to go with this CPU, since even the high-end AMD processors no longer come with one. You *can* use an older AM4 cooler, and I tried using the Wraith Prism that came with my Ryzen 7 3700X on the 5900X for a little while, but it was painful to listen to. These CPU's do just use a lot more power and generate a lot more heat... and that heat ramps up super-quickly. You really need something with a dual heat pipe setup or better, or use water cooling (I use air). I looked around and found that the Thermalright Peerless Assassin was consistently ranked in the top tier of AM4 coolers in tests, despite only costing around $30, so that's what I went with. The others that perform similarly all cost a lot more.On that note, just check that you've got a power supply that will support this processor. Either add up all the power requirements for all the components you have, or just take a Kill-a-Watt device and see how much power you're using at boot (boot is when you're usually using the most electricity). Then add about 70 watts more for this CPU vs. what you're probably using now. Obviously it's not going to be hitting those peaks all the time, but you don't want to get into a high power draw situation and have your PC immediately crash. So just make sure your PC can handle it. I have a 600 watt PSU that's about as old as my motherboard and it is working fine, but remember that what really matters isn't the total wattage your PSU is capable of but how much it can put out on the specific rails that are asking for it. If you've got a 600 watt PSU with something like an RTX 3080, then I can almost guarantee you're going to have a problem if you install this CPU and don't upgrade the PSU. I'm running a 4060Ti, which uses a lot less power than Nvidia's 3000-series cards, or most of AMD's cards.So just be aware of the power requirements, and think about whether your PSU can handle this CPU given the other components in your PC.This platform is probably about at the end of its life but you can definitely wring a few more good years out of it with the 5900X. Maybe by then AM5 will be a little more affordable.