TC-885-UA91 Can't Access BIOS after Enabling CSM Option There, Cannot Revert Setting Because of That

Hi all.

I have a TC-885-UA91. Half of the time I use this desktop for my computing needs. In the past year or so I had a Win 10 on a M.2 NVMe SSD in the M.2 slot and another Linux Mint 20 on M.2 NVMe SSD at the PCIe x16 slot through an adapter. The Win 10 was set up as the default OS. Whenever I wanted to use the Linux Mint I just use Fn+F12 at bootup to get the boot menu and selected to boot from Linux Mint. The BIOS version was R01-C3, performed the update in July 2020.

Several months ago, to test whether I could install 32-bit Win 10 to the TC-885-UA91, I did change the CSM setting in BIOS from Never to Always once. Later on, I found out I could not install 32-bit Win 10 to this PC directly, so I reverted the setting of CSM back to Never from Always. Things were fine after reverting the BIOS setting.

Some very old 32-bit programs can be run with the TC-885-UA91 but some cannot. Earlier today, I stumbled on an old program and Win 10 said it could not be run. That's why I tried to change the CSM setting from Never to Always in BIOS again to see if that program can be run.
This time the PC booted straight to the Linux Mint, bypassing Win 10. Reboot again, same result. No chance to access the Boot Menu or BIOS.

I took out the Linux Mint adapter from the x16 slot and left with only Win 10 in the M.2 slot, and all I got was an all black screen, not even the the Acer screen with the juggling ball was displayed. CPU fan was turning O.K.

Knowing things did not work out right I tried to revert the BIOS setting. There was a single short beep for POST check. The normal message at lower left hand corner for hitting Del to enter BIOS and F12 for boot menu was not displayed. The screen was all black. No way to enter BIOS or Boot Menu.

Seemed like I can only use this PC as a Linux machine now if I cannot access the BIOS again.

Anyone got any idea how to tackle such problem?

@billsey

@JackE

Thanks in advance.

Accepted answers

ttttt

I did it!

After removed the CMOS battery for two hours and reseated it, I managed to reach the BIOS. Tried to reset the CSM setting in the Boot tab, but the cursor could not reach there. Ended up reaching the Exit tab, selected to load Optimized Defaults ( F9) and Exit and Save (F10). This is simpler than originally thought that I might need to use the Clear CMOS Jumper eventually.

Now everything is back to normal. I am using this TC-885-UA91 typing this message now.

One thing to remember, not to use the CSM setting any more.

All comments

billsey

Yes, you are running into the Linux boot 'features'. When you enabled CSM that told Linux to boot in legacy mode since UEFI has disabled, which forced a grub launch that disabled the timeout for the BIOS entry. You can still get into the BIOS or F12 boot menu, but you have to be lucky to get the keypress at just the right millisecond during POST. Once you get back into the BIOS you can reset CSM to normal then use the boot menu to get back to UEFI using the Windows boot list, which currently has the Linux UEFI boot as an entry. BTW Windows 10 uses UEFI even in the 32bit version... To try a really old application, use Compatibility mode instead of mucking around in the BIOS.

ttttt

@Billsey

So far I am not lucky enough to access the BIOS, not even seeing the Acer logo screen.

CTRL+ALT+Del still works for rebooting.

I just removed the CMOS battery, with the hope that will reset the BIOS. Will wait a couple hours and put the battery back and see what will happen.

Should not mess around with the CMS setting again any more. It is strange that last time I changed it and nothing was messed up.

ttttt

I did it!

After removed the CMOS battery for two hours and reseated it, I managed to reach the BIOS. Tried to reset the CSM setting in the Boot tab, but the cursor could not reach there. Ended up reaching the Exit tab, selected to load Optimized Defaults ( F9) and Exit and Save (F10). This is simpler than originally thought that I might need to use the Clear CMOS Jumper eventually.

Now everything is back to normal. I am using this TC-885-UA91 typing this message now.

One thing to remember, not to use the CSM setting any more.

billsey

Yeah, there is really no reason to even have that option these days... It pretty much is always going to create more problems than it solves, just as Legacy mode does.

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