Keyboard not detected in BIOS but works in Windows

Whenever I re-plug my PC it turns on and off immediately and as a result next time I turn it on I see this message:

Problem is that pressing F1 doesn't do anything. Actually pressing any button doesn't do anything until I boot into Windows. The keyboard model is Accusor Speedlink connected via USB.

The only workaround is to re-plug an old clunky PS2 keyboard only to pass this screen.

Is this issue normal for old PCs (Optiplex 790)? How can I make this new keyboard work in BIOS? Would connecting it via USB-to-PS2 adapter make it visible in BIOS?

You're getting this message in the first place most likely because the CMOS battery in your system is dead. Replace the CMOS battery to stop this from happening.

It's possible your system has the "USB Emulation" setting currently set to Disabled. This would prevent a USB keyboard from working. If you never changed this setting, it's possible the bad CMOS battery has corrupted settings.

The only workaround is to re-plug an old clunky PS2 keyboard only to pass this screen.

Use this clunky keyboard to enter the BIOS settings and re-enable any setting similar to "USB Emulation". If you have this disabled on purpose you'll need to either stick with a PS/2 keyboard connected or temporarily re-enable then disable it to bypass this screen.

If the setting keeps getting disabled, replace your CMOS battery.

Would connecting it via USB-to-PS2 adapter make it visible in BIOS?

Very likely. In my experience sometimes certain keyboards don't work with certain adapters. You also may have to restart the computer to get the adapter to work properly.

It seems the battery of your BIOS died or is very low causing the BIOS to lose its information and reset to defaults causing the message.

The problem with some motherboards is that their USB initialization routine can be slow. Slow enough to not fully initialize the keyboard before the bios no longer needs it, or in case of an error, not initialize at all, as you are having in this example.

Whenever this is the case, the motherboard always has the old PS/2 connectors, and the only way to deal with a bios problem then is to connect a keyboard through PS/2. So yes, for older pc's but even for modern ones, this is expected behavior.

You can use an USB to PS/2 adapter without any problems.