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kristeva

macrumors member
Original poster
Apr 22, 2016
31
2
Hi Guys

I hope everyone is well, may I once again ask you brilliant people for some advice please?

My pimped up old Mac Pro 5,1 is still doing sterling service but I recently acquired a Mac mini M1 for music and general office admin. With this in mind I also purchased a BenQ PD2705Q monitor with built in KVM so I could run the 2 computers from the same screen.

My Mac Pro has a NVIDIA GeForce GT 120 512mb graphics card so I was hoping to connect to the BenQ via a mini DP to DP cable.

On first boot up it initially didn't detect the signal, I turned the monitor on and off and it found the signal ok. All well and good until I decided to investigate the screen resolution in system preferences. I clicked the scaled button and saw there was a resolution higher than native (1920 x 1200), yeah I know I was stupid but curiosity got the better of me! I clicked it and the screen went blank!

I rebooted the Mac and no signal detected, I tried booting in Safe mode but still got a blank screen so I installed my old screen and went into system preferences and made sure display was set to native resolution. I then reconnected the BenQ and booted up again and the signal returned on load up but annoyingly went blank again just before I got to the login page.

Annoyingly I couldn't access the BenQ monitor on board controls so I connected up my Mac mini to the BenQ which then allowed me to change the monitor display settings from 1:4 to 1:1 (Native), but again the Mac Pro lost signal on boot up just before the login page.

Any ideas as to whats happened here?

Is it somehow reverting to a higher resolution just before login? Or is the DP cable the main issue?

Cheers
 
Enable screen sharing on the MacPro5,1 so that you can control it from the Mac mini if the screen goes black again. Use screen sharing to change the display mode on the MacPro5,1 so that it is no longer black. Then restart the MacPro5,1.
 
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OP, zap the PRAM on the 5,1.
Thanks, I did this today but unfortunately no luck.

I thought I might try and connect my Mac mini to my old monitor as it has a spare D Sub mini connector. I purchased a Belkin USB C to D Sub convertor but the screen is super low resolution and system preferences wont let me change the resolution, clicking on the higher resoltions has no effect. can anyone recommend a cable that might work? Or HDMI to D sub?
 
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