[NAME]  F2 BIOS and set Secure boot OFF and set CSM ON. Then try sata operation default.  If that still has problem try sATA OPERATION ATA INSTEAD OF RAID ON. If bios isnt responding press F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 F2 F12 
A friend’s Inspiron 3847 started acting up after a storm. At first, it looked to be just a bad stick of RAM but it’s now flaky again. We bought a replacement 3847, intending to simply switch the hard drive over. When it didn’t boot, I checked the BIOS of both machines. The old one is set to legacy boot and the replacement we bought is UEFI. How can I change the setting so that he can use his old hard drive in the new machine?
Switch replacement 3847 from UEFI to Legacy