According with page 19 of the manual, OptiPlex 5090 either ships with an offboard AMD GPU Radeon RX 640 (table 19) or an onboard/integrated GPU which is either Intel UHD Graphics 630 or Intel UHD Graphics 730/750 (table 18).
The output of
lshw makes it clear that your Dell OptiPlex PC shipped with the onboard/integrated Intel GPU, even though its model wasn’t identified by the kernel (i.e. it’s not clear if the integrated GPU is either model 630 or model 730/750). I suspect that a missing kernel module may be the culprit for this.
Because table 19 reads Multiple display support matrix but table 18 only reads GPU— Integrated, I’m under the impression that your integrated Intel GPU does not support multiple displays: only the OptiPlex that ships with the offboard Radeon RX 640 does. I mean: it seems that such Intel GPU is capable of displaying the exact same screen on 2 monitors, but not capable of e.g. generating 2 different terminals/screens and then showing screen 1 in one monitor and screen 2 on the other.
Anyway… I don’t know which Linux distribution you are using, but the
i915 kernel module (device driver) is the most commonly used for Intel UHD GPUs. I’m btw positive that
i915 is the right driver for Intel UHD 630 GPU, but I’m not sure that this is the one for the model 730/750 (even though it likely is, too).
Hence, I would expect that
lsmod |grep video returned
video 24538 1 i915 to you, yet it returned
video 24538 0. Weird.
Therefore, prior to attempting to figure out if the integrated GPU does indeed support multiple displays (I think it doesn’t), it’s a priority to install the kernel module that is specific for such GPU (because apparently it’s not installed). If the module is available, then a root command such as
insmod i915 (followed by a reboot) will likely be enough. If after this the output of
lsmod |grep video still shows
0 followed by no video driver name, I’d take a look at the package repositories and try to find any package that, once installed, adds kernel support for Intel UHD GPU versions 630 and 730/750 (it may be just driver
i915 or may be two drivers). Furthermore, I would then add the respective kernel module(s) by running
Once you have the proper kernel module installed by your Linux distro’s package manager and then linked to the kernel through
insmod, if your monitors still can’t simultaneously show at least the same screen, then it’s time to check if a newer kernel provides extended functionalities.
Because I’m using XUbuntu 20.04, I investigated its apt repository. The metapackage
oem-somerville-cubone-rkl-meta is a factory/oem metapackage for Dell OptiPlex 5090/7090 computers. Its source-code informs me that it installs
ubuntu-oem-keyring and then adds
http://dell.archive.canonical.com to my system’s (i.e. local) list of package repositories. After analyzing such repository and such metapackage’s dependencies, I reached this kernel header requirement:
I mean: I don’t know which Linux distro you’re using, but in case your distro happens to provide an OEM kernel version 5.14 (or later), I would install it, because the package installer may install such kernel along with the (eventually missing) kernel modules (device drivers) that not only work with such kernel but are also required to make the Dell Optiplex onboard/integrated Intel GPU work properly (i.e. let
xrandr query its data, configure it etc.).