I'm almost there but not quite. I'd been running Yosemite on the system shown in my profile to the left. I haven't been in a hurry to upgrade, but today an app I needed told me I had to be on El Cap. I wasn't using NVIDIA Web drivers with my GT 740 because they weren't needed.
I followed the guide and found I needed to add some steps:
1) I had to add FakePCIID_XHCIMux.kext and FakePCIID.kext to the EFI/CLOVER/kexts/10.11 folder or only my front two USB ports worked. I was able to use my keyboard and BT dongle in the front ports to finish configuration, and after installing those kexts was able to move them back to the back ports. Also my external Time Machine drive showed up again after installing those kexts.
2) After installation I got to the part where the gui was supposed to start, but instead I got a spinning circle on a black screen, a second of the mouse in the upper corner, then the spinning circle again. I booted into safe mode and the system was at the proper resolution, but every time I scrolled or clicked it redrew instead of moving smoothly. I couldn't find any other answers to my problem and decided to try the NVIDIA Web drivers for 10.11.3. After reboot I was able to reach the login screen with a normal login, but the NVIDIA driver thinks my ASUS PB278Q monitor is a TV and restricts it to 1080p. Under Yosemite it was correctly detected as 2560x1440, but in El Cap it's 1080p stretched to fit the screen (overscan was on by default).
I've tried multiple things to fix the graphics problem, but I'm back to using NVIDIA web drivers and 1080p resolution. If I boot to safe mode I get 2560x1440, but not in normal mode. Some of the things I tried that didn't help:
1) Switching to OS X Default Graphics Driver - when I reboot I get back to where I was. From the text size it seems to be trying to show the login screen at 2560x1440, but it keeps showing me the text of mounting the Time Machine partition (in a verbose boot), then going black with the mouse, then back to the Time Machine partition lines. If I boot normally it will either fail completely with the circle/slash symbol or get to the GUI part and go back and forth between the spinning circle and the black screen with the mouse. I left it there for 2 hours and it was still cycling. The only way I was able to get out was to boot to safe mode and reinstall the NVIDIA Web drivers, bringing me right back to 1080p.
2) Changing SMBIOS from 3,1 to 14,2. No effect.
3) Upgrading to 10.11.4, which also entailed finding the beta NVIDIA drivers in this post:
http://www.tonymacx86.com/os-x-updates/187001-os-x-10-11-4-update-5.html#post1223399. I also had to change from OsxAptioFixDrv-64.efi to OsxAptioFix2Drv-64.efi. No change from what I reported above. NVIDIA works at the wrong resolution, no NVIDIA results in an endless loop.
With all the researching, sometimes on my phone when the computer wasn't booting, I've been working on this for the better part of 14 hours now. I'm quitting for the day.
Any advice on the NVIDIA problem? I searched tonymacx86 and Google without finding anything that helped me.