Thanks for the additional info
Couple of questions if I may;
What is the brand and model name or number of the power supply unit (PSU) in the computer.
the internal graphics card in my 64-bit Dell Inspiron 660s stopped supporting dual monitors
What is the brand and model name or number of the card that stopped working.
I purchased an AMD XFX Radeon HD 5450 dual monitor graphics card and installed it. After I did so, the original Dell card worked for both monitors for a day but reverted to working with only 1 monitor when I tried to use the new AMD card.
Bit confused by the above, are you saying that you had two AMD video cards installed working in Crossfire mode, Speccy says that Crossfire is disabled, see AMD article
here but only if you do have two AMD cards in the computer.
The voltages in Speccy look a bit off, particularly the ones I have highlighted in red, these are the voltages that go to the PCI and PCI-e video card slots and drives.
Voltage
CPU CORE: 0.972 V
MEMORY CONTROLLER: 1.488 V
+3.3V:
2.016 V
+5V
: 3.387 V
-5V: -11.904 V
+5V HIGH THRESHOLD: 2.822 V
PCI Data
Your Windows installation date also highlighted in red, since the install have you reinstalled the drivers for the MB and starting with the chipset drivers first, if not and you do so please make sure that you create a new system restore point firstl
Operating System
Windows 10 Home 64-bit
Computer type: Desktop
Installation Date: 12/10/2017 7:39:47 PM
Two different lots of drivers installed over two days, as already mentioned over the past few months a lot of people using AMD video cards have been having problems due to Microsoft updating drivers not just unnecessarily but also with the wrong drivers as well, leave as is for the moment until we have the answers to the questions asked above.
12/16/2017 Advanced Micro Devices - Audio Device - AMD High Definition Audio Device
Advanced Micro Devices Audio Device software update released
in April, 2016
12/15/2017 Advanced Micro Devices, Inc. driver update for AMD Radeon HD 5450
This driver was provided by Advanced Micro Devices, Inc. for
support of AMD Radeon HD 5450