That is basically a summary of the problem The Dell Inspiron 3847 does not come with RAID, so I tried installing a PCI-express 1x RAID card. However, the RAID BIOS never shows up. The HDDs show up when I install the RAID controller driver in Windows 7 setup, but I cannot install Windows 7. I am using an IOCrest SY-PEX40008 RAID card with a Silicon Image Sil3124 chipset.
I tried pressing the hotkeys for the RAID BIOS listed in the card's manual, but it seems to just cause bootup to freeze. BIOS also does not seem to detect the RAID card HDDs as boot options.
Storage cards option roms will not work nor will any hardware or driver be seen when UEFI Secure boot is on. Only with Legacy CSM do devices like this work. Furthermore if the Device is PCI-E 1.0/2.0 spec the motherboard WILL NOT Downclock the PCI-E bus to 1.0 speed and therefore any such cards inserted will not be "Seen" by the bios or the motherboard or windows.The 3847 has PCI-E 3.0 bus which is not downward compatible to PCI-E 1.0/2.0 cards.
PCI-E 1.0 is NOT forward compatible to PCI-E 2.0 or 3.0. On systems where said cards work the bios has set the bus to 1.0 speed and all cards installed on the bus would run at that speed.
This is also why Older Sound Cards and Network Cards and TV Tuner Cards etc do not work at all.