Black screen, loud fans but external monitor works
I bought a late iMac with a faulty drive and replaced the cpu, hard drive and ram on it. When I first started it up before opening it I got a gray screen with the question mark box blinking, I wasn’t worried because it was a basic 1TB drive I was replacing anyway. After all the upgrades I got a loud fan noise and a black screen but I have no problem hooking it up to an external monitor where I was able to use the system but the fan was still running full speed.
The computer is showing my cpu, new hard drive and ram are working fine but I cant get the internal display to show anything and the fan still runs at full speed. I bought new cables and a brand new display and nothing has worked, I took my old display and the new one and tested them with a 2014 5k and they are working fine. I want to say it’s something on the logic board or gpu but then why would I get full use on an external display?
I have also reset the SMC and PRAM as well as tried the a few different power cycle methods with no luck. At this point any help would be greatly appreciated
Update (11/09/2019)
Here is what I got from the diagnostic test from my external monitor. I checked apples website and it only says to contact Apple. Any ideas? Thanks!
Esta é uma boa pergunta?