Compaq 8100 dual screen not working

[Compaq8100_new]

Hi, my Compaq 8100 has a separate graphic card, the motherboard VGA output does not work - which is strange. Since I want to add a second screen, I bought a second hand video card (Asus HD 6450 Silent) which I inserted into the second available slot. But W11 does not detect a second screen; nor does the screen (both are Dell) seem to receive a signal from the desktop, whatever connection I use. If I remove the original graphic card and connect the Asus alone, only 1 screen is detected. Can the 8100 motherboard possibly not handle 2 graphic cards ...? Does anyone know? Or does annyone use a Compaqq 8100 with 2 screens successfully? Thanks very much for your precious help.

My config: Compaq8100
Processor Intel(R) Core(TM) i5 CPU 650 @ 3.20GHz (3.19 GHz)
RAM 12,0 Go
Graphic card Microsoft Basic Render Driver
OS 64 bits, processeur x64

[Paul_Tikkanen]

Hi:

The onboard video is disabled when a graphics card is installed.

Doesn't your Asus video card have more than one video output?

If so, you should be able to connect two monitors to two of the video outputs (for example the DVI and HDMI out ports if yours is so equipped like this one:

ASUS AMD Radeon HD 6450 (EAH6450 SILENT/DI/1GD3(LP)) 1GB DDR3 SDRAM 610839381234| eBay

If your PC has two video card slots, the card installs in the black slot, not the white one.

[Compaq8100_new]

Thank you, the Asus is in the black slot. You are correct, when connecting the 2 screens to the 2 outputs, they both work, but with the same image. When I try to detect a second screen in the W11 screen settings, it does not find it. I don't know why, as I have had dual screens many times on different desktops over the years. Maybe the 26200.8313 build of the 25H2 version is the issue. 

[Paul_Tikkanen · Accepted solution]

You're very welcome.

Did you set Windows up to extend the monitor?

Choose Your Mode

Duplicate (Clone): The same image appears on both monitors, using the highest common resolution/refresh rate. Good for presentations or demos

Extended: Desktop spans both monitors, each with its own resolution and workspace. Useful for extra work space

Eyefinity: Two or more displays grouped as one large virtual desktop, with resolution and area determined by the number and arrangement of monitors

2. Enable in Windows

Windows Key + P → select Duplicate, Extend, or Second screen only

For Eyefinity, first enable Extend in Windows Display Settings, then proceed in AMD Software

3. Configure in AMD Software: Adrenalin Edition

Open AMD Software from the Start menu.

Search Display → Display Settings.

In the Eyefinity section, click Quick Setup to apply Windows’ display arrangement.

If needed, click Display Arrangement → Rearrange Displays to adjust order.

For Eyefinity, up to six displays can be grouped per GPU (depending on card specs).

I recommend that you install the Beta software driver which was the last driver AMD released for the HD 6540:

Radeon Software Crimson Edition Beta

Revision Number

Crimson Edition 16.2.1 Beta

Second file under the W10 64 bit section.

AMD Radeon™ HD 6450 Drivers and Downloads | Latest Version

[Compaq8100_new]

Thanks, an error msg says Windows detects a vulnerable driver which it refuses to install.

[Paul_Tikkanen]

You can turn off the Vulnerable driver blocklist which I have had to do from time to time in W11.

Go to settings>Privacy and security>Windows security>Device security>Core isolation>Core isolation details>turn off the Microsoft vulnerable driver blocklist.

[Compaq8100_new]

Thank you. I didn't have the option "Core isolation" (don't know why), so I installed the Turn_ON_Microsoft_Vulnerable_Driver_Blocklist.reg from here (option 2), restarted W11, then was able to install the Beta driver you recommended above, and now dual screen works. Thanks again for your precious help.

[Paul_Tikkanen]

Anytime.

Glad to have been of assistance.

if your W11 25H2 installation is fully updated with the latest cumulative and security updates for W11, I recommend you update your PC to W11 26H2.

Each build is only supported with updates for two years.

You can be up and running on W11 26H2 in less than a couple of minutes by running the W11 26H2 enablement package that I zipped up and attached below.

Here's the info from Microsoft regarding the enablement package:

KB5121794: Feature update to Windows 11, version 26H2 by using an enablement package | Microsoft Sup...

[Compaq8100_new]

Yes, mine is on 26H2, but not the Compaq 8100, was never able to install 26H2, but now that "security" issues have been taken care of, it may work. I'll give it a  try again.

[Compaq8100_new]

On a PC without Secure Start it won't install. I've tried workarounds, none was successful until now. Been in the BIOS, found nothing useful.