I am also tryning to install El Capitan to my Dell 7348 Laptop, but I am stuck at the first step (Changing DVMT value). The link that you have provide for Backup tools is dead, but I have maneged to grab the file from other source. Anyway I run the Backup tools (as Admin in Win 8.1) and although I got error during the proccess I got the results file. The file "x32_bios-region_10.0.30.1072.bin" actually is present at the results folder, but it is not regognized by the universal IFR extractor. I have tried A00, A04 and A07 version of bios with no success. Is there a specific setting on the bios that should be done before getting the backup? Also I am very confused to the matter if I have to change the DVMT value in order to install OS-X. Is it a matter of stability for the system or a requirement for installing El Capitan (I have read somewhere that you can used a patched version in order to bypass the check by the OS instead of altering the DVMT value, which I would prefer as the system is still in warranty...).
I also read the guide http://www.tonymacx86.com/el-capitan-laptop-guides/177845-guide-dell-inspiron-i7-7348-dual-boot-windows-10-a.html, but there is no reference of backing up the bios and target the parameter for changing the DVMT value. Anyway, cause I am very noob to all this, the more I read the more I get confused, any help would be highly apreciated....
Thank you