Ok, so I wanted to check if the tests were IO bound:
- pcie ssd: Finished in 6 minutes 18 seconds
- fast microSD drive: Finished in 7 minutes 52 seconds
Clearly IO is not a real issue since the microSD card is orders of magnitude slower than the pcie SSD which would translate in reality to a delta of seconds between let’s say the 830/840 and the 850.
Still 1.8x is huge compared to the IPC improvements and the extra frequency boost. If it’s only the CPU I wonder what exactly makes it that fast.
It’s clearly not the ECC ram that slows down the Xeon E3-1280 V2 since it scores the same as the 3770K:
Maybe the answer is in these synthetic benchmarks:
Where cache and memory, arithmetic et al are from 1.9x to 2.1x faster compared to 3770 (and the E3-1280 V2)
tl;dr: sometimes synthetic benchmarks do translate to reality. In any case this was quite fun to get to the bottom of it 
wrong