BigChimp97 :
clau_aclx :
last night battlefield 4 made some updates for Mantle. Any day now the beta drivers will be available. I recomend waiting a few days, it could be worth it, until we get some test results. It is said that 290 CF got 60 % performance increase. If and until NVidia finds a way to benefit from Mantle, AMD will have a much greater performance / price report so you should take that into consideration. The only downsides for 280x are a bit more temperature and a little higher power consumption.
Since your MB supports CF but not SLI, have a little patience for real life tests on Mantle, since we're just a few days away from gaming improvements.
Mantle has been one of the main reasons that I've been considering to buy the 280x and so far it seems to be a great API, just hope the public get he same results!
As I said, last night Battlefield 4 required an 1.2 GB update, the game has Mantle integrated.... but... we need to wait a few more days for new Beta drivers that take full advantage of it. And the the benchmarks and im sure that more games will prove some differences.
Still waiting a little bit is valuable, just in case Mantle will suck and give a lot of crashes, then you will get the 770 smiling, if it works well 280x will do the trick.