Question Incompatibility between Dell U2415 Display and Gigabyte M510 AORUS PRO


Jul 28, 2011
This is really weird.

So I upgraded my PC and now I have:
Mobo: Gigabyte M510 AORUS PRO
Display: Dell U2415
CPU: AMD Ryzen 3 PRO 4350G with Radeon Graphics

The idea was that DisplayPort will be connected to Dell display and HDMI to TV. Currently the TV is disconnected because OS often thinks that TV is the primary display, having troubles initializing Dell.

Anyway, here's the problem:
UEFI is not displayed on Dell U2415. It never shows up. When OS starts, it sometimes initializes the monitor, sometimes not. Sometimes it happens on login screen, sometimes I have to log in blindly to get picture. Sometimes I have to reconnect the cable. Sometimes switching input on OSD helps.

Luckily, I have another monitor, Dell P2314Hc. So I connected cable to it and there is no problem at all. The funny thing is that I can enter UEFI setup from there, reconnect cable to Dell U2415 and I retain the picture.

Okay, so my Dell U2415 is faulty, right? I asked Dell to replace it and they sent me very similar model (I think it was U2415A or B...). Exactly the same problem.

So there must be something wrong with this model, right? Well, I took the monitor to my neighbor, connected it to his PC and everything worked perfectly.

Of course I checked already 3 DisplayPort cables. I also ordered a cable without 20 pin problem (Delock).

Before I upgraded PC, this Dell U2415 worked with my older PC using DVI-D to HDMI cable correctly.

Any ideas? I'm a professional IT worker but I've never seen anything like that...