HP 800 mini G3 black screen when install Windows 7 BIOS CSM/MBR disk

Thanks SIW2,

I tested install. It's only Windows 7 install media working on HP 800 mini G3 MBR disk. Other medias no go. HP is unique.

Its final size on USB is 6.25GB, though must be downloaded onto a 32 GB USB drive. hence I later moved its copy to a 16 GB USB drive (even 8GB should be ok)

I don't know how to use the tool and how to obtain the info on Windows 7.

I was uploading the file here to you. but failed due to its size big (boot.iwm about 213MB).

Update

the media downloaded from HP web/HP_RECOVERY works on HP computers only. even though it looks generic.

I tested the HP media on non-HP computer install. the install went freezing-up. (In contrast, Dell Windows 7 install media/DVD works for non-Dell PCs).

I was thinking the HP media should have drivers of USB3, NVMe, and could be useful to install other new PCs.

Looks no go. HP is unique.

I got my 2nd HP 800 G3 (from sn, newer than my 1st one).

It can run Windows 10/11 only. no way to install Windows 7. its CSM mode is disabled (grey). while UEFI mode wouldn't boot Windows 7 install/HP_RECOVERY (error: selected boot image did not authenticate. solution per HP is to enable CSM mode).

my 2nd HP 800 G3 looks more like Lenovo PC. cannot install Windows 7. only takes Windows 10 HP RECOVERY.

So, same HP 800 G3 model, both shipped with Windows 10/11. 1st one can run Windows 7. the 2nd one cannot.

Thanks,

I have tried and my HP G3 BIOS has been flashed to latest version. but the problem stays.
(CSM/UEFI select boxes grey out. cannot be clicked)

If boot Windows 7 install USB. "selected boot image did not authenticate." I was expecting, at least it boot then I apply UefiSeven. but no luck.

If Windows 10 install USB. no problem. therefore it's running Windows 10/11.

I wish it could select CSM mode. that would be easier for PC backup. and I could keep two HP G3 same backup policy.