MP 7,1 Monitor shows Apple logo and half progress bar before going dark.

[b17777]

Bought a used 7,1 16-core, 96GB, 2 TB, MPX 580X. Plugged in an old ACER S231HL via HDMI. Would chime, Apple logo, show half status bar, then go dark, with the monitor scrolling through the inputs looking for a signal then go to sleep. I tried the HDMI from my 2019 MBP with USB C dongle and monitor would scroll looking for input. Took a HDMI to DVI dongle from Mac to monitor and booted up fine. Came with Sonoma installed and I set up the computer, installed my PCI Dante card added a SATA 3.5 disk. Tested the Dante card, everything was working normal, booted multiple times as I installed drivers and audio software. I then updated to Sequoia. Everything still working after update.
Next day took it to work,hooked into Dante network sending and receiving audio normally no booting problems. Next day I came in and same issue as in the beginning, partial start up screen then dark searching for signal.Tried multiple times with both HDMI ports on Mac Pro. Had old ELO touch screen that only has DVI so I plugged the cable into that and booted up. Everything ran great all night recorded 37 tracks and hosted some Waves plugins, ran great.
I plan to pick up a new monitor tomorrow that will have HDMI, display port and USB C inputs and go out and test it again.

Would resetting NVRAM have helped this ? Or anything else besides after new monitor to try ?
I've searched the forums but never came across this problem.

 

[Regulus67]

Would chime, Apple logo, show half status bar, then go dark, with the monitor scrolling through the inputs looking for a signal then go to sleep.

I had a similar issue with one monitor, years ago when I used PCs. My guess would be it is the monitor that is the problem.

 

[reader50]

I ran into problems using a cheap Best Buy Insignia TV as a monitor. Direct connections from the graphics card to HDMI input would fail. The TV monitor did not like the signal from my RX580. My theory is the monitor demanded recent versions of HDCP on the input signal, which is optional and should not be enforced when used as a monitor.

My solution was to buy an active adapter. This one made everything work again. If you don't have a free DisplayPort on your graphics card, you'd have to first adapt an HDMI port into a DisplayPort using an adapter like this (out of stock).

Active adapters have solved a few computer-to-monitor issues I've run into, often making more resolutions available. The adapter I linked is compatible with the audio signal too, if you use the monitor's speakers.