Thanks again. I'm not looking at anything as an investment. I bought the "never used" i5 MBP solely for the purpose of using it's chassis (I really despise seeing the dented top case on my original i7 MBP). I bought the i5 MBP from a reputable seller on eBay for $100 USD (+ $10 shipping). The sale also included a "never used" 85W charger. The seller bought the MBP new in 2010 with the intention of making the switch from Windows, but decided (very early on) that that wasn't going to work out for him/her. So, it sat on a shelf for 12+ years. Everything has virtually zero hours on it (the battery only has 11 charge cycles, but it's toast since it's been sitting so long). New screen, new keyboard, new logic board, new super-drive, etc (the unibody doesn't have a mark/scratch on it).
That’s impressive — both its condition and also the price you paid for it. I ended up paying only USD$8 less (excluding shipping) for the late 2011 13-inch i7 (whose battery had an appreciably higher, but still low 290 cycles on the original battery and 93 per cent health). You did very well with that buy, given the benefits of the 15-inch form factor.
Do logic boards get "tired" ? I'm not sure that the ~10% performance increase of my i7 board is worth my effort of swapping it into the i5 MBP. The modest increase in speed/performance is not as important to me as reliability. Will my "tired" i7 logic board be less reliable than a "fresh" i5 board ? Or do logic boards not get "tired" ?
It’s sort of a bell curve.
Generally, logic board with factory faults are the units most likely to fail early in their lifetimes (and what standard manufacturer warranties mean to cover). Then, boards which didn’t fail at the start will tend to be stable, solid units for many more years to come. After heavy, lengthy use, extant boards may become more prone to ageing in logic board substrate, solder points, heating/cooling cycling, and the like.
My 2011 i5, as noted before, has lived an extensively busy life and very nearly all of it has been powered on in some form. It was my rig for field research and primary data collection for writing a masters thesis (which was written on the same Mac); then for technical writing; then for making, working, and colour-adjusting film scans from a dedicated film scanner; then more tech writing; then a DJing rig; and then an in-home music server using the S/PDIF output (after the battery failed and the system auto-downclocked to 1.0GHz). In between, I watched plenty of films and TV series. It’s travelled with me across a dozen major cities, across four nation-states, and across two continents. It’s been thrown into bike messenger bags and laptop bags, and used in, literally, all climatological conditions (save for a hot desert).
The problem to emerge with mine was issues with the second SATA bus — the one reserved for the SuperDrive. I could have just ignored it and bought a second, larger SSD to replace the SSD with my start-up volumes (the SSD which lived in the hard drive bay), but I needed to first isolate how the failure was occurring, because I wanted to know. For reasons not clear or visibly evident on the board, the second SATA bus handled reads fine (as always), but was erroring out on writes to the second hard drive I had in lieu of the SuperDrive).
Given all the heavy, constant usage over nearly twelve years, I’m guessing my i5 board is nearing the other end of that bell curve, where things to fail
will fail with greater frequency — not due to age so much as total running hours. Two other places my i5 appear different from the i7 I just bought are also electronic components whose efficiencies diminish over time: the LED for the keyboard backlight and the LED strips for the display. As these are solid-state diodes, just like all the diodes, transistors, resistors, and capacitors on the board, it’s not surprising these have diminished over years of constant use.
It’s a topic to come up semi-regularly with older Macs, many discussed over on the
PowerPC Macs forum. Some are more notorious in their long-term failure rates than others, such as Power Mac G5 motherboards (which had an especially
high rate of failures at the start of their lives, as well).
So the short answer to your question is “sort of”: logic boards can get “tired” in a sense.
