Z840 does NOT go to Startup Menu after <ESC> key pressed

[RKolmanator]

We have a Z840 in our system that occasionally needs to boot from a USB Flash or USB DVD.

However, getting to the Boot Menu to manually specify the USB Boot device is unreliable.  Pressing <ESC> when told to do so DOES earn a text response on the window "Entering Startup menu..."

Then the system merrily boots from the Hard Disk.

Is there a specific TIMING when to press <ESC>?  The change to the prompt text is taken to mean "successfully pressed and detected" but such is proven false when the Window 10 boot continues from Hard Disk.

Thanks for any ideas, suggestions, clarification.

[DGroves]

are you using a USB keyboard? some usb based keyboards have very cheap usb controllers in them and as such have all sorts of subtle timing related issues

if you have a ps2 keyboard, i recomend you use it as even cheap ps2 keyboards seem imune to strange timing issues

[RKolmanator]

Thank you DGoves for that suggestion.  It appears to have been a contributor, but not the whole solution.

After switching to the PS2 keyboard, the problem continued to manifest (Cannot get to Boot Screen).  However various experiments now seemed to get to the Startup Menu more frequently.

I've isolated A sequence that does repeatably get to the Startup Menu.

From an account with Windows running (Windows 10 Pro) select the "Restart" option.  When the "HP" screen presents, and the text in the lower left corner appears, press and hold [ESC] until the CPU beeps for the key buffer filled.  I then press <F11> just to make the OROM display full screen.  Easier to spot transitions.

This combination has reliably resulted in the Startup Menu being presented.  6 times without fail.

However, from "Power Off" the same sequence completely ignores the key buffer full of ESC and continues to Windows,  booting to completion.  It does not bring up the Startup Menu.

I've demonstrated it for a co-worker multiple times as well. 

So the mystery is why or what in a "Power ON" takes a different path then a "Restart".

[DGroves]

try replacing the monitor display and/or changing video input between DVI/HDMI

also try swapping between DVI ports on the card and also if HDMI ports change betweem also

change display video cable