The Gigabyte Z97X-SOC Force delivered 29.3GB/s for a huge 2GB/s lead over the Asrock Z97 boards. Having checked memory timings and frequencies, we're not sure how the Gigabyte Z97 board came up with the extra performance. Either the Z97X-SOC Force is unusually fast or the Asrock boards are slow, perhaps due to immature BIOS revisions. Unfortunately, we don't know until we test more boards.
Thankfully, despite the difference in memory bandwidth performance, both the Asrock and Gigabyte boards delivered virtually the same L2 and L3 cache performance. It is interesting to note that the slightly higher clocked Core i7-4790 wasn't any faster here.