Hi there,
 
perhaps has this been monitored by fellow Z97 Stinger owners?
 
HW: EVGA Z97 Stinger MiniITX with BIOS v1.08, i7 4790k, 16GB 1600 MHz RAM, default BIOS settings, no OC (yet).
OS: Win7 Ultimate 64bit with EVGA drivers installed and Slackware64 14.1 with Kernel 3.10.55
 
The NIC (intel i217-LM) behaves really strange. After booting Win7 the NIC sometimes (in 2 out of 10 boots) is disfunctional (e.g., no DHCP leases are accepted, no network connectivity at all, Win7 just shows the "red cross" on the LAN icon). Then again in 8 out of 10 cases everything works perfect, fast and reliable. 
 
Same thing with Linux: Though ifconfig shows the adapter as eth0 and manual IP assignment does work, no network functionality is given (no DHCP leases accepted and so on). This happens with the 3.10.55 stock e1000e.ko driver as well as with the latest Intel v3.1.0.2 drivers. No visible errors or warnings in dmesg.
 
My fix: Putting the PXE-Boot-Device as the first boot device so the systems tries to boot via DHCP before booting the actual OS from disk (although this slows down the boot process by 10 seconds or so).
 
...but why the heck is it only working this way ..? :-(