Machine doesn't POST when DisplayPort is connected

[Iloque]

My machine doesn't POST if the DP cable is connected. I suspected the Pin20 problem, but the cable is CAC-2068 Cable, no 20 pin connected. 

 

It does start, the fans start spinning. Also, just 2 days ago, all was working fine, had been for about 2 months since the last upgrade. I did spot a Windows update in there somewhere. But I am not sure if it's related. The thing is, it manifests as a Pin20 problem. It boots fine on HDMI. It boots fine if I disconnected the power from my primary screen. If I boot, see the POST on the second screen and then plug back in the DP screen, it also works fine. 

If only the DP monitor is connected and I start the PC, the screen comes on, shows a single cursor, goes black and nothing ever happens again. I don't hear the audio pop on, can't enter the BIOS, nothing. The quick diagnostic LEDs indicate a VGA problem.

I've done the nVidia firmware fix on the 1080. No dice. I installed the latest nVidia drivers, 496.49 as I was still on 6 monhts old drivers, no luck there.

 

This is the rig;
CAC-2068 Cable, no 20 pin connected
MSI-Mortar MS-7C94 B550M MORTAR
GeForce GTX 1080 GameRock
AMD 3800X - 32 GB

Anyone got a clue?

[DoctorNick]

2 minutes ago, Iloque said:

My machine doesn't POST if the DP cable is connected. I suspected the Pin20 problem, but the cable is CAC-2068 Cable, no 20 pin connected. 

 

It does start, the fans start spinning. Also, just 2 days ago, all was working fine, had been for about 2 months since the last upgrade. I did spot a Windows update in there somewhere. But I am not sure if it's related. The thing is, it manifests as a Pin20 problem. It boots fine on HDMI. It boots fine if I disconnected the power from my primary screen. If I boot, see the POST on the second screen and then plug back in the DP screen, it also works fine. 

If only the DP monitor is connected and I start the PC, the screen comes on, shows a single cursor, goes black and nothing ever happens again. I don't hear the audio pop on, can't enter the BIOS, nothing. The quick diagnostic LEDs indicate a VGA problem.

I've done the nVidia firmware fix on the 1080. No dice. I installed the latest nVidia drivers, 496.49 as I was still on 6 monhts old drivers, no luck there.

 

This is the rig;
CAC-2068 Cable, no 20 pin connected
MSI-Mortar MS-7C94 B550M MORTAR
GeForce GTX 1080 GameRock
AMD 3800X - 32 GB

Anyone got a clue?

Try running DP firmware update tool for 10 series and older https://www.nvidia.com/en-us/drivers/nv-uefi-update-x64/

[Iloque]

11 minutes ago, DoctorNick said:

I've done the nVidia firmware fix on the 1080. No dice. I installed the latest nVidia drivers, 496.49 as I was still on 6 monhts old drivers, no luck there.

Thanks, but I did that already. Didn't help.

[DoctorNick]

3 minutes ago, Iloque said:

Thanks, but I did that already. Didn't help.

Have you tried. Shut off PC. Turning off PSU. Remove both cables and only inserting DP?

Also is the display Samsung by any chance?

[Iloque]

I did. Turned of PSU. Removed cables. Booted with just the DP screen an Ancor ASUS PB278. No dice.

 

What really bothers me, is this started yesterday. Evening before that, no problems whatsoever. Exact same system.

 

[DoctorNick]

24 minutes ago, Iloque said:

I did. Turned of PSU. Removed cables. Booted with just the DP screen an Ancor ASUS PB278. No dice.

 

What really bothers me, is this started yesterday. Evening before that, no problems whatsoever. Exact same system.

 

Hmm maybe try a different cable or something? Guess you have tried all ports?

[Iloque]

43 minutes ago, DoctorNick said:

hmm maybe try a different cable or something? Guess you have tried all ports?

Guess I'll have to. Don't have one handy unfortunately. HDMI's to spare but only a single DP cable in the house.

I did try the other port yeah, no changes.