HEDT
In my experience there's usually two schools of homelabs: Thrifty, power efficient, making the most use of what you've got or what you can get hands on, oddly enough probably has more thought put into it and well crafted. The other is ex-enterprise gear, loud, inefficient; balls to the wall.
Personally, I've been in the ex-enterprise side of gear for quite some time, but I would argue never fully gone into that side, especially for the network side of things, as I've preferred less audible gear, namely network switches that run 24/7.
But what started the foray into enterprise level gear was HEDT.
For the unitiated, it's essentially prosumer level gear. For camera users it's going from Canon 600D to a Canon 5D, not quite a 1DX, but above that comfortable dollar range and into the small investment.
I wasn't so early as to be starting watercooling with aquarium pumps, or dual socket pentiums, but I was in the shift towards more cores, EX58 to be precise.
While far from my first build, this was my first step into the EXTREME -
CPU: Intel i7-920
Motherboard: Gigabyte EX58-EXTREME
RAM: 12GB DDR3
GPU: 2x Gigabyte GTX285
PSU: 1000w Zalman
Case: Antec Twelve Hundred
Now this wasn't the top of the top, you could have had dual 295's for effectively quad SLI, the board supported 24GB of RAM, and at the time the i7-965 Extreme was the top, the i7-990X came later.
Largely, the point I'm trying to make is computing is much less exciting than it used to be. Sure, you could argue that if your first proper build is a Ryzen 9800X3D, it's going to be a blast. It's going to rip way harder than the prebuilt or computers handed down from siblings / parents. However, it's missing the fanfare that consumer computing once had.
This is where my next broad categorisation falls into place. There -was- 3 types of packaging, and this partially comes into the excitement of it all.
There's always been the small box white generic box, with some graphics / branding, typically your budget friendly gear ie; your A/BXXX series motherboards.
Then you've got your mid to high tier items and the boxes back in the day made a statement. Sure, it might have been some weird Final Fantasy esque looking characters or some sort of Alien, but these were the big boxes, not only are you paying for high end product, it makes it feel as if you're getting something substantial.
Lastly, is not exciting, it's the brown box, and this means business, no frills, all compute.
While not quite as crazy as say the Voodoo days, and the era of big box gaming, but I still have my EX58-EXTREME box, and it dwarves anything I've bought in the past 10 years.

Regardless, the boxes may be one aspect or gripe, but the other huge thing, and one of the main components that has left the market, is trying different things.
Who cares if it's a dud, that's why the guys on the bleeding edge are at the edge, to see what can be done, and where it's going.
Gone are the days of the nonsensical add-ons that come with the board to improve cooling. Ports like SATA Express, which had next to no devices that could actually utilise it. More recently U.2 ports, there was a very brief window where you could get a U.2 port on a consumer level motherboard, now it's relegated to workstations if you're lucky, servers at best.
Now, yes... I could have gone to a Threadripper or Epyc build for my latest iteration, but there's an astronomical price difference between the top end of consumer compared to the current version of 'HEDT'. Where the CPU alone could cost more than your entire build, for honestly not that much more performance to your day to day computing needs, in some cases less.
Earlier, I mentioned that HEDT was essentially a small investment, which is something most people would have to consider before delving into. If you're going to do it, it's something you're passionate about. That too I would argue is largely gone as well. Which I'm in two camps about, as to whether it's good or bad.
The good news is now all components are expensive and a small investment... That's not a good thing at all, but the point I was going to make before my realisation was at this point in time, we're probably at the best possible place to be for barrier to entry. You can still get excited about computers, there's still -some- innovation, and I guess if you're young enough, you don't really know what you're missing.
The downside for me, is the excitement. Would I go back to a prebuilt computer? No. But this is pushing me more into the server grade territory, because at least it's exciting. What crazy I/O can I play with? Now, I already have a few servers, Cisco, Supermicro, Tyan - However, I would not use these as my daily driver, they are grossly inefficient, extremely loud, but damn it, they're fun.
What sparked this was I finally retired my X299 system, which is probably Intel's last exciting HEDT platform, it had U.2, OLED display, 8 DIMM slots, actively cooled VRM, while SLI is dead, it has enough lanes to support it. Essentially, a dream for expandability and multitudes of configurations.
As a quick side note, another benefit to the current iterative generation of computers, where everything is same-same, it was arguably one of the smoothest new builds I've done.
The new build -
CPU: AMD 9950X3D
Motherboard: Asus ProArt X870E-Creator
RAM: 192GB DDR5GPU: EVGA RTX3090
PSU: 1200w EVGA 1200 P2
Case: Corsair 900D

You'll notice that I've only upgraded the platform side of things. I was going to go for a 5090, but the state that the 50 series is in, I will be definitely waiting for the series to mature.
It would be remiss of me to not mention a board that was brought to my attention. There's a X870 ROG board that has a SlimSAS connector, which is cool and that technically makes my U.2 / U.3 point moot, but it comes at the cost of an x4 lane. Which feels like it defeats the purpose, you've now taken away a commonly used x4 lane, for a port that is- well, as I mentioned earlier relegated to server boards.
I definitely do appreciate the idea, but it bothers me that it's not additive. You're not upselling to the likes of me, you've just made it inconvenient for most others.
I get that timing, length, etc of traces is all a factor for all things in the current generation of PCIe, but bring back PLX chips, give me more lanes and expandability.
Be bold, be exciting.
Addendum
I had some thoughts after posting this, for example while not entirely relevant to HEDT. The complaint I had about manufacturers not trying things has really been pushed to the small form factor side of things / SBC.
For example there's been a huge shift towards hats and accessories to expand on, that really take things to the next level. Very much that enthusiast focused approach.
And to further my point of the importance of boxes, that's why Apple has an unboxing experience, I'm not wrong, and Apple definitely isn't wrong.
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