Is this due to there not being enough power? I have tested both cards and they work. I have a Rosewill Series HIVE-750W Continuous power supply, a SAPPHIRE 100364TXSR Radeon R9 270X graphics card, I don't know the name of the second card as i got it second hand but I believe its a few year old gaming card. there are 2 3.5' and 3 2.5' hard drives installed also.