Lately my laptop (HP g42 247sb) screen is damaged, so I hook it up with an external monitor (LG something) and it works fine now.

The only annoying thing is I cannot navigate the BIOS menu for some tweaking because the BIOS not shown on the external monitor, instead, it only shown on the broken laptop screen, and it only output to my external monitor when Windows/OS is logged-on.

So, is there anyway I can force output during BIOS/BOOT/POST to my external monitor?

Things I have done and didn't work:

  1. Set my LG monitor as primary display on both window properties and Intel Graphics panel

  2. Enter the BIOS (F10 key) and press the Fn+F4 key (change display output).

  3. Disable and uninstall my internal screen (broken laptop screen) using device manager and restart, but Windows (BIOS?) install it back on log-on.

  4. Closed lid/Magnet on sensor.

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    If you can find someone with an identical machine, then you can do a blind walk through: Both people do the same thing on both laptops, the one with the working screen guiding the other. – ctrl-alt-delor Sep 19 '12 at 8:49
  • In addition to what richard said. Some BIOS allow do deactivate the internal Screen. If you are able to achieve that blindly it could be working after a reboot. – Langhard Sep 19 '12 at 9:02
  • Thank you for the input, but is there any other way than that because finding one with identical machine is quite hard, maybe a bios map? – gamer Sep 19 '12 at 9:17
  • It sounds like its time to replace te laptop and/or send it in for repairs. – Ramhound Sep 19 '12 at 11:36
  • Have you tried contacting the laptop tech support? It'll be a PITA but they might have some solution for you. Can you get the BIOS information (version no. etc) then possibly find more information about the BIOS, you might find information on external displays. Otherwise from all the other answers I see, probably just get the screen repaired? ... – KDecker Jul 10 '13 at 21:30

Please try to close the lid right after you press the start button. This works on my HP 6730b here, i can see the BIOS then.

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  • It didn't work,look like the bios(mobo?) won't even send output to vga during start-up/memory test, but thank you for your input. – gamer Sep 19 '12 at 9:54
  • This seems weird to me. Your notebook should output your BIOS to the external screen... Do you have another screen to test? Maybe its an issue with unsupported screen resolution / framerate on the LG Monitor during the bootup process..? – Langhard Sep 20 '12 at 8:52
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    This works on my Acer Aspire E 15 too! Thank you. I shared your solution, among many others I tried, here: unix.stackexchange.com/a/312326/106621 – Antonio Vinicius Menezes Medei Sep 26 '16 at 6:16
  • Closing the lid also worked for me on a 4540s, thanks. – speedyrazor Feb 6 '17 at 11:19

A closed lid should force the output to the external monitor.

Most laptops detect a closed lid with a magnet and a sensor. There is a small magnet probably somewhere on the top edge of the screen, and a sensor in the area of the body of the laptop that it would be near when closed. You can use a small refrigerator magnet placed on the sensor to trick the laptop into thinking it's always closed, while still having access to keyboard and buttons.

You can find the location of the magnet by either taking off the plastic cover on your screen, looking for disassembled pics online, or just moving a magnet over the outer edge where it likely is.

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  • Didn't work, I press the start button and quickly closed the lid... even entered the bios(F10) tap some key to verify I'm in BIOS (by the beeping sound it made,I think I'm in BIOS) later I press the start button again to logon into windows and comment your answer. – gamer Sep 19 '12 at 9:52
  • It may not work if you close the lid while already in the BIOS. Try finding the sensor location while you are in windows, that way you can have it think it's closed when it's turned on. – DaleSwanson Sep 19 '12 at 9:54
  • Okay,I will try to find the sensor location now. Thank you for the quick reply. – gamer Sep 19 '12 at 9:57
  • also: at some notebooks usb keyboards work at boot time to enter bios – Langhard Sep 19 '12 at 9:59
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    I found the sensor and place a magnet on it(the internal monitor goes off) then I restart but nothing happen, the external monitor just come up at windows logon. – gamer Sep 19 '12 at 10:20

You say you're having problems trying to get the "boot with lid closed" method working; I just want to make sure you're actually trying to boot with the lid closed, and not pressing the power button/quickly closing the lid.

If you are able to boot into Windows 10 and log in on the second screen, try the following:

  1. Connect an external keyboard and mouse.
  2. Go into Settings

    System -> Power ->Advanced Power Settings -> Change what closing the lid does ->
    Set both "When plugged in" and "When on battery" to "Do Nothing".

  3. Close the lid. Your Windows login session should stay up and visible on the external monitor.

  4. Restart the computer, leave the lid closed. (I opened a command line prompt and typed

    shutdown -r -t 0

    but a restart from the Windows 10 start menu should also work).

You should see the boot screen on the second monitor and you should be able to use the external keyboard to get into the BIOS.

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  • To make sure I understand this correctly: You are saying that setting the "closing the lid" will modify not just Windows behavior, but behavior at BIOS level, too? – mafu Aug 5 at 1:24
  • @mafu No. It will, however, enable you to reboot the computer with the lid closed. I can't speak for all BIOSes, but they are pretty resilient: the BIOS wants some screen to show the startup status on. If the lid of a laptop is closed, but the laptop is connected to an external monitor, it will fall back to using the external minitor. – Spencer Aug 5 at 12:55

According to page 38 of the manual you can switch screen output between the display devices with FnF4

I expect this also works for the output before POST has completed.

screenshit of page 38 of the manual. Relevant part marked.

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    This is promising, assuming that the key works during the BIOS phase and is not limited to Windows (the backlight key probably works at a hardware level, but some of them may work in conjunction with a hotkey program in Windows). – Synetech Sep 11 '13 at 14:54

I had the same problem. I took the bezel off my screen and disconnected the laptops monitor. This forces the computer to use the external monitor and shows the bios menus.

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  • This was the only thing that worked for me (though I disconnected the cable at the main board end). I dunno what happened as before I could use Win-P to "project" to external monitor and F10 did similar, but rebooted and nothing I tired could switch to external screen. – ensignr Nov 15 '18 at 9:17

I had a this problem with a 2011 ASUS A53SV laptop which has a broken screen. The laptop was being used like a desktop with an external monitor. It had an old hard drive, and I wanted to upgrade it to an SSD.

Things that did NOT work initially:

  • disconnecting the display cable from the motherboard to try to force the other screen to be used

  • closing the laptop lid and attempting to spam F2 to get into the BIOS

  • attempting to navigate the BIOS blind (gave up)

  • pressing F8, the ASUS laptop's function button to switch displays

  • trying both HDMI and VGA cables

Might be forgetting some, but basically, the laptop absolutely did not want to show the BIOS on the external screen until the last option in this comment, resetting the "CR2032" battery, was done.

After taking the battery out and putting it back in, I followed this by doing the following: got Ubuntu on a DVD and took the hard drive out so only Ubuntu would boot from the DVD drive (afterwards I found out that the BIOS didn't allow booting from USB), then tried pressing F8 to switch display in an HDMI and then DVI connection. Only the DVI-to- monitor connection worked for this laptop, but it was relieving to see the BIOS on the screen for the first time after spamming F2. It may be notable that the laptop motherboard was connected to the broken screen via display cable when this occurred.

With access to the BIOS, I changed the boot priority to DVD reader first.

Finally, I cloned the OS, Windows 7, from the old hard drive onto the new SSD and put in the new SSD. After putting in the SSD, W7 was bootable right from the start, and I was able to reinstall W7 via DVD.

I think the most important part was resetting the CMOS battery and using Ubuntu and DVI cable for this problem with my specific laptop. Hope this helps others with laptops that have broken screens.


edit: I'm not a hardware repair expert and am not sure what exactly helped the BIOS appear in the end, but I'll try to distill out what I think are the important parts

  1. reset CMOS battery
  2. After that, try every port your laptop has for the monitor including the DVI, which worked for mine's.
  3. Try an ubuntu boot disk and pressing the laptop specific function button to switch screens if that doens't work.

These were the most important, I think. If there are any specific suggestions for clarifications I'm open to them.

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  • I'm not sure your answer actually describes a valid process for accessing the BIOS on a second screen. – Burgi May 29 '19 at 8:11

Had the same problem with my HP laptop. Tried closing the lid, F4, etc, but they did't work for me. It was booting into the Windows login screen, but refused to output anything to HDMI during neither startup nor login.

I figured out a pretty simple solution when I was playing around with the start-up buttons (for my particular model, a touchscreen HP Envy), which may or may not work for other models.

I connected the HDMI cable before starting up, then repeatedly hit the ESC key during POST (right after power is turned on; this directs you to the page for selecting boot options), which somehow routed the display to the external display, and I was able to navigate into BIOS accordingly on my external display.

This might not work for other models, but it might be worth a try since it doesn't involve taking away parts, shutting (in my case, a badly shattered) screens, etc.

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I also had this problem with my (fairly old but still quite decent) HP laptop. The screen had broken a few years back, and a new one was too expensive, so I sawed it off (USB wifi antenna ~€10-€15). I use it to play media on a tv, which was fine until I wanted to do a clean install after upgrading to windows 10.

But I figured out a solution! And I think it'll work for laptop with broken but attached screens too:

I tricked my laptop into thinking it had a closed lid by placing a magnetic strip along the front part (of the bottom half), and it worked! It let me enter BIOS the usual way (depending on your laptop, of course) and automatically showed it on the external monitor.

NOTE: I also used a wrench to twist the hinges to the closed position. I don't tink this made any difference in my case, but there might be laptops with hinge-sensors? I don't know..

Hope this helps!

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