Here’s the issue with a lower price Mac tower, using a Core i5/i7/i9...Apple simply doesn’t want to push everything through the PCH and that’s what would be required.
Using the iMac as the example...the Core i9-9900K CPU in mine has x16 lanes of PCIe 3.0, all of which are dedicated to the GPU,a Radeon Pro Vega 48, to have the optimal GPU performance. This exhausts the PCIe lanes of the CPU and in a typical PC tower, you have either one x16 slot and one at x0 or you can support 2 GPUs at x8/x8 By splitting the bandwidth. Everyone here knows this, right?
Any remaining PCIe slots in a PC (or mythical Mac) tower are routed through the PCH (Intel Z300-Series for 9th Gen CPU-based PCs) which has a total of x24 lanes of PCIe 3.0, which are allocated to the vacant PCIe slots on the motherboard, typically in and x4/x1/x1 scenario with an extra x4 m.2 slot, maybe more, somewhere on the motherboard.
But Apple made that decision for you by integrating a single Titan Ridge controller for a pair of Thunderbolt 3 ports and installing their proprietary slot flash storage in place of leaving a m.2 slot open for the end user.
But what I’m hearing is that a lot of users on this forum want those slots, preferably x4/x4 AND the super fast storage and the Thunderbolt 3 ports, which is where Apple says...nope. Simply, nope. Because they’ve seen what happens when you try to push super fast SSD and I/O AND a couple of PCIe x4 cards (10GbE and another m.2 carrier card) through the PCH, only to have it slow down to a crawl trying to shove all that data through Intel’s puny, pathetic and tiny DMI 3.0 bus to the CPU. Something they have been doing since the inception of the Core i-Series.
This alone, should be enough for users to understand why Apple will never build a Core i-Series based tower. The engineers, like them or not, are paid to make the best decisions in the interest of Apple and of you, the users, which is not to try and crush every ounce of data through DMI from the PCH to the CPU and watch performance go in the sh!tcan as unsuspecting users try to cram more spinning rust SATA storage and 4 cheap-o PCIe SSDs on a single carrier board through a inadequate pipe. It‘s not what the engineers are paid to do, it makes Apple look bad (PC vendors don’t care, they are simply pushing tin), and it hurts customer trust. So, they went with the iMac and the Mac mini on the mid- and low-end and then moved to Xeon on the high-end where Intel deigned to put in x64 lanes of PCIe 3.0 on the CPU die itself.
As for the other parts, they would be common amongst the iMac and a mythical Slotbox Mac (GbE, USB 3, 802.11AC, BT 4.2/5.0 and DRAM is usually 2 or 4 slots, with support up to 64GB or now 128GB of DRAM.
So, basically, the only real objections to an iMac is that Apple chose your display and GPU for you (not some sh!tty Acer 24” from Costco) and made the storage proprietary (again, not some cheap Adata NVMe crap on special at New Egg) and took away a couple of slots that weren’t going to perform well anyways, because, if you really needed them to perform well, you wouldn’t be buying a Core i-Series PC, right?
I’m pretty much left with the answer that rings true once you get to the heart of the matter. You want to pay Apple the least amount of money you possibly can for the privilege of using macOS and getting free updates every year while tarting it up with cheap components and then demanding help from Apple Support if it falls down and goes boom because you put cheap crap in it.
And please spare me the arguments about customer choice, they didn’t work on Tim Cook, because he isn’t leaving money on the table (’cause it’s his job NOT to leave money on the table), it’s about getting what you want as cheap as possible and it’s on Apple to figure out how to stay profitable, am I right?
Hopefully, Acer, Dell, HP and Lenovo will learn this lesson in the next few years and start jacking up the prices on PCs so that they can stay in business and restricting the crap components that they put into their builds, because that’s what I keep hearing from the so-called Windows PCMR people is the reason that we’re having Windows issues. It would behoove the Top 4 PC OEMs to rethink the race to the bottom and start building themselves a sustainable business instead. Anyone who doesn’t like them doing that would be better off building their own rig anyways, or at least that’s what I keep hearing bellowed around these forums.
So go do it. Otherwise, I’ll trust that Apple knows what they’re doing, even if I don’t always like it or don’t always want to pay for it. Meanwhile, Apple isn’t going to give you what you want, because they figured it out years, even decades ago, after nearly going belly up trying to compete in the shark-infested waters of the PC that staying alive means swimming against the current.