AnarchoS, may I ask why you need to have 2 integrated LAN ports? Is it because you do not like to have add-on cards, or because your mainboard is filled with them and you have no suitable free slots for them?
Have you considered using an add-on card? If the above reasons are not an issue, then you can go for it...
In fact, I use only an add-on card and disable the integrated one. While many may scorn me, it may even have some advantages: it may be galvanically somewhat more isolated from the chipset. I know that it may now sound dubious because the schematic layout is similar... Fortunately, the times when such functionality was integrated in the southbridge are over, as the induced electricity in a (typically) long Ethernet cable from a lightning strike could electrically break down the LAN controller chip. And perhaps even more, who knows. If it were integrated in the southbridge, it would kill the whole southbridge, thus killing the whole mainboard. I believe this is why manufacturers have abandoned the practice. Nowadays the difference in the galvanic integration between an add-on card and an integrated one is much smaller, if any, but who knows, it may still make a difference.
However, you can bet that if lightning strikes a lightning rod in your vicinity and given a sufficient length of the LAN cable, then without a surge suppressor, the LAN controller will be damaged, no doubts about it. I remember such a case in a small observatory—all the connected NICs, whether integrated or add-on ones, were damaged and unusable. And so were most power supplies. But otherwise the computers were undamaged. In fact, a friend of mine who runs a computer shop says that he keeps a lot of NICs and power supplies in his store precisely for this reason and he giggles that he watches the weather reports, checks his stockpiles and orders the NICs and power supplies accordingly, so that he may have an ample supply of them from his store...
Oh, that was so grossly off-topic...! Back on topic:
the GA-890FXA-UD5, revision 3.1 is unavailable, as far as I know. Oh, I would be so glad if it were!
Perhaps the real reason why they dropped the additional LAN interface is that it was raising the cost of the mainboard and taking some precious space on the back panel—but here, it is probably the necessity of another NIC controller chip, as there still seems to be some empty space left...