I doubt you because you made a non-technical correlation between two KNC customers and an unrelated forum post saying that the same brand had popped a motherboard.  News flash, every manufactured PSU on the planet has popped a motherboard, usually to no fault of its own.  Further the HX850 is a very stable PSU, we use them for 12V supplies in the lab and its what I have run on a dozen Jupiters for over a month.
One thing I did notice, which I overlooked in the product pictures during ordering is that KNC did not properly ground each ASIC board.   The PCI SIG clearly states that 6 pin auxiliary connectors are for 75W draw and 8 pin added two additional grounds, making it _SAFE_ to draw up to 150W.  Note: don't be a moron and read the spec incorrectly, the PCIe edge connector itself can deliver 75W, the 6 pin aux gives an _additional_ 75W, for a total of 150W.

The reason people have been popping boards is the combination of sloppy AC and the boards drawing too much power with not enough ground.  It has little to do with choice of power supply.  I altered my boards by scratching off a portion of the solder mask and soldering the additional two grounds.  Then I sampled the VRM output voltage for two hours.  End result less jitter.  And I'm running off of 208V synthesized AC from a large bank of Liebert equipment.

Long story short, if it didn't come straight from KNC's mouth, don't believe Orama's non-nonsensical, uneducated babbling.  KNC never recommended one brand over another, the only thing they indicated was a minimum capacity, which was 850W.   Until they post somehting on their website, ignore Orama.