I have been trying to install Fedora 25 on a desktop with an i5-6600K CPU and dual graphics (Intel Sky Lake Integrated Graphics and Nvidia GeForce GTX 970). It's a dual boot set-up with Ubuntu on another partition. It is NOT a notebook, so I don't think it's Optimus.

Fedora ran fine on the 4.8.6 kernel, but would only boot to Gnome's gray background after upgrading to 4.8.15. Thinking it must be a nouveau problem, I decided to install the Nvidia driver. I rebooted back into 4.8.6 and performed the following steps:

dnf update
dnf install kernel-devel kernel-headers gcc dkms acpid
reboot
echo "blacklist nouveau" >> /etc/modprobe.d/blacklist.conf
vi /etc/sysconfig/grub (to make GRUB_CMDLINE_LINUX read "rhgb quiet rd.driver.blacklist=nouveau")
grub2-mkconfig -o /boot/grub2/grub.cfg
dnf config-manager --add-repo=http://negativo17.org/repos/fedora-nvidia.repo
dnf install -y nvidia-driver nvidia-settings nvidia-driver-libs.i686
reboot

It installed the 375.26 driver, but then booted into "Oh, no" screens using both 4.8.15 and 4.8.6. Later, I tried installing drivers from rpmfusion and the Nvidia site, but they booted to black screens and, when I used the Nvidia .run file, I couldn't even Ctrl-Alt-Del to a tty session. What can I do to get more information about what is going wrong?

Finally, when it was running OK with 4.8.6, I did notice one weird thing that may or may not be meaningful. The Details panel in Gnome settings listed only the Intel graphics card but said nothing about the Nvidia card. Yet when I run "lspci | grep -E "VGA|3D", both show up. Is Gnome somehow not seeing the Nvidia card?