Sure it's not STOCK. This card default run at ~23.x Mh/s. For 28.x Mh/s you have to modify the BIOS as I mentioned above.

For your concern about part/build quality I have to say : Slightly yes.

I got my hand on 2 mining cards : ASUS MINING-RX470-4GB (Hynix) and ZOTAC P106-100-6GB (Samsung) and they both "look cheaper" than normal gaming card.

BUT they ran flawlessly for over past 3 months like my other rigs ( gaming card ) so ...maybe just "look cheaper"

PWC is a good choice, many of my friends choose PWC and run at 30 Mh/s (Samsung)