Chosen Solution
Hi everyone, Does anyone know why it takes about 10 seconds (black screen) to show Apple Boot Logo in iMac 27 2013? I got macOS Catalina on non-Apple PCIe SSD with adapter. I’ve pointed out the Startup Disk in Settings as a Boot Disk - done reset and……… it was showing that Apple Boot Logo right away - but from shutdown - power up - it takes about 10 seconds to show Apple Boot Logo - which is very weird. I got even macOS Catalina installed on genuine Apple HDD (without any PCIe SSD) and STILL same thing. I had 27” iMac but 2012 with same non-Apple PCIe + adapter SSD and it was showing Apple Boot Logo right away. I’ve hold D for Diagnostic and no errors at all. I’ve done PRAM reset. Thank You Bart
Give this a try: Go into your Date & Time settings un-check the time server setting and manually set the date and time so its correct. Now disconnect the power cord for the night (longer if you can). In then morning plug in the cord and check the date and time is is correct? If not the PRAM battery is bad. So your settings are not being held so the polling proves takes place instead of what you defined. You’ll need to take the logic board out again as its on the back side iMac Intel 27" EMC 2639 GTX 775M GPU Logic Board
As to why it drained, I’ve seen some issues with the M.2 adapters its also possible it was just bad.
