Booting on external display

[r2006]

I have a Thinkpad Edge 535, bought it about 6 months ago.

I swapped the hard drive with an SSD cloned to the original hard drive.

The laptop works flawlessly, except I noticed something very weird:

If I connect an external display via the HDMI port, this works as intended as long as I connect the external display when the laptop is on. With the proper settings (i.e., when closing the lid, ‘do nothing’), I can keep the laptop closed and still be able to attach a keyboard and mouse to work on the external display.

Now, the weird behavior: if I reboot while I am on the external display with the lid down, the startup hangs. Sometimes it can take 20 minutes to boot to windows, and the windows boot animation is extremely slow, as if the computer is struggling to boot. Once it boots, it is very sluggish and choppy.

Most of the time it does not booth though, it just hangs there with a blank screen. If I open the lid, the LCD screen is also blank.

If I remove the HDMI external monitor, the computer boots normally and works well again.

There is a bios setting that allows you to boot to an external HDMI display, I tried that with similar results, the boot starts on the external display, but it’s slow (we are talking 15-20 minutes) and the computer behaves strange once it boots. If I disconnect the external display, the computer simply does not boot, and I need to change the boot display settings back to “LCD” to have it boot normally.

I have never seen this behavior with any laptop, and I have a few at home, all of them boot fine on external displays with the lid down.

Any idea what might cause this ? Could it be a Lenovo-software related issue ?

[TTY]

Hallo,
welcome to the forum If the original, rotating hard drive came with Windows installed by the factory, does the notebook show the same behaviour if you boot from the original, rotating hard drive?