Hi guys, so my mac pro 4,1 flashed to 5,1 and on high sierra has been running the original radeon 512mb 4870 but i decided i wanted to upgrade so i went for the sapphire pulse rx580 8gb as i had seen people installing them. Instead of the original model they sent me the “lite edition” with no dvi output. Anyway i connected it all up using the 2 x 6 pin mini to 8pin cable i bought turned it on and as you can probably guess, nothing. No fans spin on it, nothing appears to happen. Now i know on these the fans only spin when under loads but i thought maybe they would even fire up for a second as it powers on maybe somebody can confirm that. Anyway it goes through the normal boot process, makes the chime you normally get before the apple logo so it sounds like its booting and theres just no video. I have tried the hdmi and the display ports. No joy in either. I can put the card in a windows pc and test its working when i come home from work but it was brand new and sealed so id say the card is probably ok. I can put the old 4870 back in and it boots straight up. I have tried resetting the pvram but it doesnt seem to work with the new card in but still works fine with the old one in. Anyone any ideas in something i may be missing? Has anyone used an rx580 lite edition? Id imagine its the same drivers and architecture just minus the dvi and the clock speed is marginally slower 1350 instead of 1366 i think. I appreciate any help going. Ive read a few posts woth similar issues but no real conclusion . Thanks in advance