I would struggle to ascertain the day-to-day difference between GPT-5.4 and GPT-5.5 tbh. Also, imho, Fable is highly hyped, I don't think it is dramatically better than Opus 4.8. Maybe my tasks and interaction with AI is relatively simple (i.e., lots of Rust programming, Linux system engineering stuff).
I run a 13900T unlocked (meaning, it runs 35W TDP at idle, 1.1ghz, but is allowed to peak to 210W for up to a minute, with the hugest Noctua D14something I could fit on it). It runs at ~29c idle, peaks to 80ish celsius at 210W (~4.5ghz over all cores - songle core peaking to 5.3ghz).
For a time I ran it 24/7 without suspend. It's a big system, lots of disks, expansion cards, etc. If it doesn't suspend, and doesn't do anything remarkable, it uses about ~5kWh per day. Needless to say, it suspends after 60 minutes now (my daily energy usage went from ~9 to ~4 kWh).
Can relate, a while ago (around 2016) we bought 7 second-hand dual opteron 8439 (12 cores! no ht) desktops with 64GiB of ram in them, added pcie nvme adapter, for about ~850 EUR (including 21% vat) a piece.
We have been using those systems since then and they are really amazing performers (linux and bsd, many java apps, jetbrains IDEs, etc). This is totally because of how efficient and minimal modern Linux and BSD distros can be, by the way - even with modern desktop environment like Gnome 43!
Only downside is the powerdraw. They idle at 180 watts, s3 sleep is still 150 watts and on BSD idle is 240 watts! This wasn't too much of a problem before the whole energy crisis thing, because electricity was quite cheap (around 0.19cts per kwh). But with prices touching 0.80cts pet kwh, it becomes untenable quickly.
We currently Wake-on-LAN these boxes only when we need them and they auto turn off after 1 hour of idle.