I'm not denying any of that per-se (Power figures will vary per system), simply saying you need to look at the bigger picture in terms of hardware features
Even taking into account a £100 difference in power costs per year (13p / kwh is high, but still..), you're conveniently forgetting the new option will cost £300 - £400 more upfront.
If we then assume a lifespan of 5 years (optimistic IMHO) & similar price differentials each time you upgrade, over a 10 year period you're looking at a cost of £20 p/a extra or there about.
To me that's worth it
Again though, this by no means suits everyone and makes vast amounts of assumptions.
Do your own sums on the costs / benefits.
13.3p/kw all in is cheap - up till a few months ago it was the cheapest combined deal including tax/standing charge in the market available to me (Hint: it's the comparison value, not the unit cost), but it does vary by region, if you live next door to a power station, your transit costs are lower.
As to £3-400 more you seem to be conveniently ignoring the new cost of your hardware, used parts to used parts, my chip was £64, the x99 board £68, 8GB RAM was £50 and a cooler/case/PSU brought the total to £220ish (though most were from my parts shelf from previous builds so in effect I only paid out for the CPU/Board/RAM), it saves just under £110/yr (assuming you do nothing with yours and I run Plex and other related dockers) vs your DinoServ, so unless they paid you several hundred pounds to take it away and run it at idle for 5 years, or you really, really love IPMI/ECC, then i'm going with 1366 being dead to anyone who doesn't get free power/hardware. Then again, if you actually paid anything for the box and pay your own power bills, thats just silly
