I have the same machine (with lower specs though) and did install Fedora 20 on it.
It would also not boot correctly because of KMS (kernel Mode Setting) incompatibilities with the nVidia Quadro FX1800. In the boot screen (grub) I edited the boot line to add the
nomodeset setting to disable KMS and be able to boot. But it has an impact on the Nouveau driver which cannot use the full resolution. I decided to install the Nvidia binary drivers instead.
To edit the boot in order to solve your issue, when you see Grub, hit the "E" key on your computer. You will then be able to edit the boot commands. Then use the arrow key to look for a line starting with
linux /boot (...) go to the end of the line (there should be the keyword
splash written) and add the option mentionned above. By pressing the keyboard combination of "Ctrl"+"X" the system should use your custom boot and it should hopefully work.
Once you boot, update
/etc/default/grub and modify the following line as suggested below (by adding the above option):
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset"
Save your changes and now "install" tre new Grub configuration by issueing the following command:
I was never really interested in KMS, as previously I always had Intel GPU, so it was just working. But I think you don't loose much without KMS, it removes the "screen flickering" upon boot and maybe a few more seconds boot duration. It should have no other impact AFAIR but for the Nouveau driver it basically disable it as well.
Btw and off topic:
I haven't benchmarked the SAS RAID controller integrated to the motherboard, but I would doubt it brings much benefits. I have not configured any RAID using the SAS controller, but I have used Linux software RAID for the boot and swap partitions, and BTRFS for the rest (although I would advise you to use Linux software RAID for the rest as well given BTRFS maturity).
Linux software RAID is really performant and flexible, you can define RAID per partition (so having a RAID1 for /boot and / but RAID 0 for swap and /tmp and /var/tmp). The only drawback compare to a real RAID card is the high-end one would have a battery backed controller (which is not the case of your on-board SAS controller).
I am still struggling with my configuration, I decided to plug the HDD to the SATA and not SAS controller. When plugged to the SAS controller the 2 HDD are "named" sdc and sdd because the USB live CD is seen as sda and I have a USB card reader which takes the sdb. The problem is when I remove the USB disk, the letter of the drives changes (to sdb and sdc) and this does not play well with the default Fedora grub installation (which already did not like too much that I put the / under btrfs...). By putting the HDD on the SATA controller, they are "registered" before the USB or SAS devices, so they get sda and sdb naming and it does not change on reboot. I know that one can use UUID and labels for identifying drives, but I had no desire to fix the default grub configuration.
I tried just out of curiosity 2 other Linux distributions (just as Live USB). Ubuntu 14.04.1 booted fine with the nouveau driver but ArchLinux 20140801 showed a black screen after the Grub prompt and it was stuck in this mode. It is my first time with a Nvidia card on Linux, and this is shitty!! I had no troubles in the past with Intel or AMD GPUs using the opensource drivers.