The HP ENVY h8-1400ex circa 2013 was issued under WIN 8 OS. Only an exact replacement motherboard would work with the current hard drive, which you upgraded to WIN 8. I would suggest you take the unit to a locale shop, and get a second opinion.
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HP Envy 8 5010 Tablet (2) HP DV7t i7 3160QM 2.3Ghz 8GB Printer -- HP OfficeJet Pro 8620 Legal Custom Asus Z97D, I7-4790k, 16GB RAM, WIN10 Pro 64bit, ZOTAC GTX1080 AMP Extreme 3 fan 8GB RAM, 500GB SSD, Asus PB287 4k monitor, Rosewill Blackhawk case and 750W OCZ PSU.
This motherboard is beset by an unnatural number of problems and people with common sense don't want to buy a straight replacement board to continue their misery... So the question for anyone with enough money to buy a new motherboard is:
In the universe of new motherboards, is there another board that fits these mount points and face-plate, in this case?
The matter of the OS license is not part of the question and is easily remedied, don't you think?...
Now, since you're an "Expert," and I am just a wandering minstrel, I shall take it upon myself to answer the question for him, and for you...