Computer won't post on reboot / restart

The <esc> key does not get you into BIOS on the GA-890FXA-UD5. That key is for exiting submenus or exiting BIOS.
The <delete> key gets you into BIOS.

I corrected my original post. I didn't have the machine on when I wrote it. I realize I'm probably unclear as to what the bios setup menu means, as well. I just mean the text that lists the options for getting into bios setup, changing boot order, etc.

Do you have a MB speaker attached? what beeps does it give you.


But I would suggest you test the components by removing them one at a time and boot. e.g., pull the GPU, boot. check the beeps (should be series of long beeps).
Pull the memory sticks one at a time and boot. (one long, one short is memory or MB)

The only time you want to use the {Reset Button} is only if Windows hangs/freezes. If you also mean when you Restart {not Reset} it hangs then depending upon where it freezes it could be a Driver/Periphial causing a hang. However, that contradicts your statement "My computer boots up fine."

S1 & S3 are 'Sleep' modes and S3 is the best/lowest power option.

Also, there are 4 revisions for you MOBO - which is yours? - http://www.gigabyte.us/search/search.aspx?kw=GA-890FXA-...

BIOS:
3.1 FB minimum
3.0 FB " "
2.1 F6 latest only
2.0 F6 " "

Also, sometimes USB Keyboards are not always 'seen' with the BIOS or can be 'seen' sporadically. Try a PS/2 Keyboard.

You need to be a little more clear  

If you press the rest button, on the next boot you're gonna get a screen that asks if you want to boot into safe mode or what ever. Is this what you're talking about? If so, this is normal right after an improper shutdown.

Pressing and holding the reset button for 4 seconds causes a hard shutdown, but on reboot the system will start normally unless Windows is missing a .dll or .sys file, or, on my machine "F8" is pressed after POST.