Are you checking your BIOS settings for POST display output?
If you have the web drivers installed, and are on them (check your boot flags, nvda_drv=1 should be among them) you should be able to boot in on any of the cards display ports, just make doubly sure you are on the web drivers, have the correct boot flags, and in BIOS have the internal graphics disabled and the display port set to your cards PCIe slot (1 I'd imagine), you can also disconnect any display cables from your MB to make sure you aren't sending competing signals, though if your settings are good you shouldn't need too.
I just had to reinstall (clover mistake... sticking with unibeast/chimera for a bit until I understand clover a bit better and get a second HD to play with), here is what I did this time around, which worked just as well as what I mentioned on page 14.
With the boot flag nv_disable=1 I installed OS, multibeasted, rebooted, downloaded web drivers and installed them, rebooted again with nv_disable=1 just to double check they made it through a reboot. At that point I switched over to the web drivers via the Nvidia Preference Pane and double checked in org.chameleon.boot.plist that the nvda_drv=1 boot flag was present. I shutdown and rebooted into BIOS, disabled IGFX, changed POST display to PCIe 1 (card) saved and exited. Upon exiting BIOS everything worked fine, have HDMI off the 970 and all is well.
I hope this helps in some way, because beyond this I probably won't be able to help much, still grasping a lot of this stuff, but having an awful lot of fun in the process!