Radeon R9 M270X 

The speed increase from your R9 270X CF setup will be noticed, greatly, where you should be doing 1080p at 60FPS without a problem, and even 1440p at 60FPS+ and some 4K gaming if you've got the display or TV that supports that resolution.

The 2 x SAPPHIRE R9 270X Vapor-X cards are a potent setup in Crossfire, so I would recommend upgrading to something of equivalent power - but a single-GPU solution.

Otherwise these drivers do contain a handful of other Crossfire fixes, including fixes for Total War: Rome 2, Alien: Isolation, and Shadow of Mordor.

The X99 Killer series from ASRock is more of a gaming oriented lineup with features such as Killer LAN and LAG Free USB / PS2 ports.

To start off, the ASRock X99M Killer features the LGA 2011-3 socket supporting Intel’s upcoming line of Haswell-E high-end desktop processors which will be available to consumers along with the X99 chipset based motherboards on 29th August 2014.

When it comes to building and configuring Core M, Intel likes to refer to their efforts as the “Fanless Challenge,” reflecting the fact that their biggest goal with Core M is to comfortably get the processor in to 10” tablets under 10mm in thickness that are passively cooled.

The end result no doubt limited what performance optimizations Intel could integrate into Broadwell’s design, but it also functionally reduces power requirements for any given performance level, furthering Intel’s goals in getting Core performance in a mobile device.