I don't intend to start a debate on whether a PC is suitable for a pinball machine. I understand the pros and cons of each architecture (disclaimer: my work is specifically on embedded ARM device, so I'm quite knowledgeable).
But I can build a three display output (and more) ARM based system with equivalent graphics capabilities for the purpose of a pinball machine in a 30W enveloppe with an operating lifetime under full load of 5 years, 24/7. And I can add some additionnal capabilities on top of it, image processing being one of them, but not only. That's kind of the whole reason why Apple is using ARM extensively, including in their Macbook line and ditched x86.
x86 brings is essentially ease of development and reduced engineering cost (especially custom motherboard requirement as is the case for Spike 2). As of today, from the pure capability standpoint in a pinball machine, there is little rationale to put a PC, but from the cost of development there definitely is (that, plus the fact that when DialedIn was released, indeed embedded device capabilities were far lower than where they are today).
ARM platform bring better integration, lower power consumption, longer operating lifetime. And for that matter, Stern Spike 2 architecture allows them to have as many display as they want conceptually, so DialedIn 3 screens setup is not something they would not be able to replicate easily should they want to. But engineering cost is way higher. It's a 50k dollars figure at a minimum to build a fully integrated ARM based custom system. Stern Spike 2 development likely costed way more than that, since they built a whole architecture around it (node, communication bus, etc).
when Pinball Brothers selected a PC for their Alien remake, the whole reasoning was likely engineering cost (at the expense of BOM cost though, from what I could see on their system architecture it's not exactly cheap)
So bottom line using a PC is perfectly legitimate, even if not optimal (my DialedIn is NOISY compared to Spike 2 next to it) in my opinion, but can be justified by lower engineering cost.
What I do challenge however is the use of a "consumer" type motherboard and graphics board.
Consumer products are designed with ONE directive: cost. They need to achieve the minimum warranty required legally at the lowest cost, and that's absolutely it (except for gaming motherboard). Which means it's super unlikely it will last for 20y, at least not all of them.
Using a graphics board with a regular PCI-express slot in a mechanically constrained environment, especially with regards to shock and vibration, is really really not a good idea (as we have seen with users reporting that the card had unplugged itself from it's slot). There are industry grade standards to adress precisely this type of concern (MXM being one of them, but not only).
And lastly: supply of these consumer parts do not last forever, whereas in embedded (even in PC space) it is traditionnal to supply components for 5 years at least, 10 years more often than not.
When these parts are not available anymore, should the motherboard or graphics board fail, you're toasted. And speaking of which, I could actually not find replacement boards on JJP website itself. You can't find them on Marco either (at least I couldn't).
One will argue that you could find some on ebay since it's a consumer product, true enough, but for how long ? Especially the graphics board, which is not exactly a standard model (it's a low profile board). WPC machines have been around for more than 20y, and you can still find boards for them. People have been designing replacement CPU board that work out of the box.
It's a different story with a tightly coupled SW/HW as is the case here
I appreciate the fact that JJP is bringing new capabilities to their released machine (Scorbit being one of them), as do many other JJP owners (I have a DialedIn by the way), but so far I have not seen a company commitment to upgrade the BSP (stands for "Board Support Package", ie the combination of BIOS, kernel and filesystem that make the whole thing work) to support different type of HW (especially graphics). And no it's very very unlikely it will work out of the box (try using JJP image on a brand new motherboard with a brand new AMD graphics board see if it works). I tried in a VM, could boot to the main bootloader, but no further.
Maybe some will step in and hack the BSP to make it work on alternate HW, but at the cost of these machines, shouldn't this be the supplier responsibility ?
If JJP state that they can (and will) add support for new motherboard/graphics board, then they will be one step closer to true customer care: allowing the customer to replace parts at a later time with different type of HW. It's a HW maintenance dream. But it has an engineering cost to JJP, with little to no return (except customer satisfaction).
True enough, part availability from Stern is also a concern (and cost !), but at least we have a solution for the foreseeable future. I can buy a Spike 2 board on Marco or Stern 2 easily. I do agree the same question will be raised in 10y.
Anyway, that was a rather long post to state my point of view
Constructive comments welcome, please let's avoid a flame war.
Regards