I have a Gigabyte B75M-D3V running if it matters an i3-3220 processor with 8GB of 1600MHz ram that wont put a display out even for bios use if i use my Gigabyte R9 270X 2GB gpu. It does however work with my Sapphire R9 390 GPU... I would prefer to be able to use the 270X to leave the 390 for my windows pc. I have eliminated the PSU as an issue as it can power the much more power hungry 390 without any problems. So any ideas?
Also the 270X works perfectly in my windows machine
Have you tried clearing the CMOS? Really weird issues can often be fixed doing that.
All the things I can think of that are worth double checking:
Not plugging in the video card correctly. Try reseating it, and a different PCI-E slot.
Not plugging in the power correctly. Try a second rail if applicable.
Not enough power in the PSU. Try another PSU. Peak power draw != idle power draw.
Try a different video output technology from the video card to the monitor/TV, like DVI/VGA or HDMI.
It may be a BIOS priority issue. It may be necessary to boot using display out from the iGP and then manually change output to the video card either in the UEFI or OS. It should be labeled as "Display Priority: IGP-PCIE-PCI" or something like that. Resetting the CMOS should fix this however.