1380mhz is not a heavy OC. That is most likely the in game boost clocks of that card out of the box. You can likely get another 10-15% out of it without any trouble.
I think 15% might be pushing it, but the important thing is that the 980 Ti doesn't have much more headroom than the 390 so we can probably expect the 390 not to lose ground with OC.
I don't recommend ANYONE sell their panel to swap vendors if you invest in Gsync/Freesync. It's a wash then. Does it matter if you're getting 42 FPS and an R9 390 user gets 10 more FPS than you at 1440p? You're still in Gsync range, so it's all gravy baby.
I'd consider it going from Gsync to Freesync because the Freesync screens tend to be cheaper. I wouldn't consider it going the other way. That's still a heavy decision to have to make.
Its never been that it can't do DX12, the issue is it can't do async compute even though NVidia is selling it as a card that can.
You can see the DX12 gains without async compute in Ashes.
Yeah. It's very very important to remember that. NV is already gaining. They'll gain more when they make a contemporary architecture ready to take full advantage, but even now, DX12 is a gain
for all gamers. AMD users gaining more does not change that NV users are gaining, and that's fantastic news. Performance isn't a zero sum game, and there's room for both sides to win.