Optiplex Desktops

[PrajThePro]

I currently have an AMD Radeon RX 6400 plugged into the second PCIe slot on my Dell Optiplex 7040MT. It works fine when I first boot up into Windows 10 while being plugged into the gpu via HDMI. After rebooting, video is not outputted to the gpu at all. But if I plug into the apu, video is outputted. I would like to note that in the Dell BIOS, there is a setting called Video Controller. It says, "This setting is visible when multiple video controllers are connected to your computer. Three options are below. The auto settings defaults to the onboard video controller." The three options in the BIOS settings are Auto, Intel HD Graphics, and ATI Radeon HD Graphics. Auto was first selected even with a gpu installed while the hdmi cable was also plugged into the gpu. Changing the video controller graphics to ATI Radeon HD Graphics seems ok at first. After you save the settings and leave the BIOs and reboot the computer, the computer does not give a video output through the gpu. Switching to the onboard graphics even doesn't display video out. No video is outputted whether it's plugged into the gpu or even the motherboard. The only way to resolve this is to fully unplug the gpu from the motherboard let windows boot up, shut it down, plug in the gpu again and plug in the cable back into it. It then boots up fine as if nothing had ever happened. This is really irritating and not efficient. Is there any way to possibly fix this dumb issue?

Current build:

Windows 10 x64

32GB DDR4 2133MHz

Intel Core i7-6700 3.4GHz

AMD Radeon RX 6400

WD 1TB SN570 Gen 3

[bradthetechnut]

When the PC is working, try downloading the latest driver for the RX 6400.  The latest driver is dated 6-20-22.  https://www.amd.com/en/support/previous-drivers/graphics/amd-radeon-rx-6000-series/amd-radeon-rx-640... 

If that doesn't work, I know not the most convenient answer, but try a different GPU.

Note:  Onboard graphics won't work with GPU card installed.

Optiplex 7040 Spec Sheet.pdf 

The 7040 was first introduced in 2015.  First thing, you might want to change the size 2032 CMOS battery if it's 5+ years old.  Bad batteries have a habit of causing problems that are difficult to troubleshoot.

[redxps630]

Re: Is there any way to possibly fix this dumb issue?

try clear cmos settings via RTCRST clear jumper on 7040 MT motherboard (#23).

[bradthetechnut]

If you do as redxps630 suggests, battery should be replaced anyway if it's 5+ years old.