I have the OWC adapter with a 2TB Pioneer SSD installed in the x16 slot (I know it is marketed as x4). I get about 1200mb/s which is more than enough. I highly doubt you would notice a practical difference in terms of another Intel Mac. Most Intel Mac SSDs that are soldered run at this speed.
So lets say you get a 1TB SSD, OWC Adapter 128GB of Ram, a Vega 56 (Pretty much the best you can get) and the best CPUS
CPU 2x X5690 - $75
OWC Adapter - $35
SSD $100-200?
Vega 56 - $100
128GB RAM - $80
So about $500 to max it out... Which honestly isn't terrible. If your plans are this or your 2014 Mac mini I would pick the Mac Pro in a heartbeat. Honestly though Having an M1 Max MacBook Pro, the ARM Macs are lightyears ahead of the Mac Pro dinosaur.
so IMO
Mac Pro > any Intel Mac
Mac Pro < any ARM Mac
I appreciate you taking the time to look at all of this! And yes about $500 through way and other type sites for sure. And I seriously considered that as well. And yeah, that amount isn't terrible at all to max out a super powerful machine.
It's really coming down to though how much I want to spend (money/time/energy-both physical and electrical) upgrading a machine that is not going to give me the performance of a smaller newer machine that I'm trying to emulate.
Just last night I was using the 3.0 expansion card I put in the 5,1 to Ofer data from an internal HDD onto an external usb 3.0 drive and it was hovering at around 80MB/sec. Fine; not the worst of course. However, I put that same internal drive into an enclosure, then connected the 3.0 external and the enclosed drive to the mini's 3.0 ports and was getting between 115-135MB/sec xfer speeds.
I would also pretty much need to get an upgraded Wifi/BT card to keep it upgradeable (as far as OCLP is concerned) but that will only last so long based on the Xeon's incompatibility with AVX2 (which the mini has).
My 5,1 has been incredibly useful for sure. I used the combo HD-DVD/blu-ray drive along with MakeMKV to fill up my iTunes library with a bunch of 1080p movies converted using handbrake (which would be more difficult and time-consuming on the mini for sure), I did some design work for case artwork, 3-d modeling, Autodesk type stuff for car design..etc. the expandability is fantastic and so are the storage capabilities. All that being said; I don't design any more, I have burned all of my movies and now I use the digital download codes to get them in iTunes or just watch the 4K version either through AppleTV or through my actual 4K devices. I realistically will not use my 5,1 for PS or xbox remote play, and the stark difference in electrical energy consumption between the two machines I have is Crazy.
Do you really think the 5,1 is better than say...even a 2018 Mac mini i7 maxed out? As far as basic use as a primary home computer with no professional level work is concerned.
And it could be that I might just be doing all of this to simply decide to upgrade to a M series mini or machine and that would be fine too.
I think I have finally learned that I need to actually buy the version of the computer that I need when I'm buying it instead of saving some money at the time and then needing to upgrade earlier than potentially necessary.