Would it, in theory, be possible to complete upgrade the logic board?

You could always try these guys in China https://www.pcbway.com/ according to Northridgefix they offer to make custom boards..... long shot but it may cost 4 arms and 4 legs to get one made especially to your requirements.

Other boards are obviously designed for particular casings, so there are numerous things that 'won't be in the exact position' down to the holes where the screws would go to fit it in the casing. And then the technology to make stuff like the track pads and keyboards work as intended. Dosdude did something quite unique on a 17" before https://www.reddit.com/r/hardware/commen...

Sorry this series uses a custom logic board and not upgradable beyond the Core2Duo. The next in the 17” series also is not upgradeable beyond Sandy Bridge i7.

Keep in mind there is limits within the OSs these systems use which then limit you on what applications you can use or even get.

I too shed a tear when my two systems finally failed as I was expecting more than they could handle and couldn’t run any newer Applications I needed, I now use newer 15” MacBook Pro’s.

Yes, unfortunately, you cannot really 'upgrade' the motherboard as there are limits. The motherboard on its own costs pretty much the whole computer, so you may as well treat yourself and buy a new Mac.

It's an interesting idea, but even if you find a logic board that fits in size, you'll need to make sure the new logic board is compatible with the original connectors, screens, keyboards, trackpads, and other peripherals.

It is theoretically possible, yes. If you happened to find components that somehow just happened to be compatible with each other. You don't just need parts that are compatible with the cpu, you have bus sizes and speeds, formats all kinds of things to take into account, and on top of that they need to work with each other. So practically, no. haha

That's a great idea! I had a similar thought before and reached out to a PCB supplier in China, https://greatpca.com/. They replied that the connectors and interfaces would be completely different, requiring custom adapters or cables, which could be quite complex. Additionally, matching heat dissipation, power supply, and physical space is also a necessary consideration. Furthermore, the firmware and drivers may not support the new logic board, leading to potential system issues. While it's technically feasible, the work would be very time-consuming and complicated, and it might not be worth it.