MSI GTX780 Lightning was at stock, it was not overclocked, it's clockspeeds are comparable to many other non-reference GTX780 which are cheaper so it's not special at all in that regard.
Those overclocks don't sound right for stock cooling, most GTX780 max out at 1200-1250, if you get to 1300 your lucky and even then probably not game stable. I'm going to presume your overclocking numbers for the R290 are just as unreliable.![]()
Gibbo's numbers are quite reasonable for the 290
I have four stock Asus 290Xs and they can all hit 1250/1625 on air.