I am on F7 bios, intel i7-4771 processor, using onboard graphics,G.Skill TridentX,2X8Gig memory. Win 8.1 OS on Samsung SSD 840 EVO 1TB drive and a Samsung 840 256 gb SSD and trying to use 2 1TB WD Caviar Black drives, CoolerMaster 850W power. In my previous system all 4 drives were powered up at the same time. Have been trying various BIOS settings, updated to F7 bios from F4, still same result. I can add the other drives after booting and they will operate ok, I have ACHI on. Then after shutdown and rebooting ,it wont power up until I unplug the WD drives.