sorry to revive an old thread but I have a Xeon 1230 v3 (Non-refresh Haswell) and I'm fairly confident it is soldered, because I can't get the lid off and I've delidded a dozen Ivy and Haswell chips using the same "vice" method with a 2x4 as the hammer wedge directly after removing the chip from a burn (so the die is hot)
Since the lid doesn't come off without literally breaking the chip, possibly removing the die from the LGA, it can only be joined by solder.
Another dead giveaway the Xeon's are soldered is the lower idle and slower "build-up" temps. Where say, an i7-4770K, spikes to 60-70C pretty quickly, a Xeon 1230v3 spikes to 50C and hovers in the 50's for awhile before getting into the 60's, more in line with the i7-4790K with its improved (but still not soldered) interface material.