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When the system POSTs, it doesn't display any options for entering the system setup.

The official manual for this motherboard claims that you need to press <Del> to enter setup, and I've tried this a dozen times without success. I've also tried <Ins>, <F1>, <F2>, <F3>, <F4>, and <Esc>.

What is going on here?
Does anyone know what I need to do to get into the system CMOS setup?

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Do you use a USB or PS2 keyboard? – Snark Oct 8 '09 at 10:05
@Snark - I use PS2 keyboards and mice for all of my servers, whenever possible. I have a few handy for times like this. – Giffyguy Oct 8 '09 at 16:33

If for some reason setup is disabled or something went wrong, you could always pop your CMOS battery (looks like a watch) out and put it back in. This will reset the CMOS.

Note: This will reset all of your CMOS/BIOS settings, so be careful.

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This is a brand-new motherboard, fresh out of the box. I might try resetting the CMOS, but I assume it comes with factory-default settings to begin with. – Giffyguy Oct 6 '09 at 20:26

Some CMOS are different.

The common F< key> entries that allow you into CMOS options for ASUS are:

  • F2
  • F8
  • F12

Sometimes < Del> is used on ASUS boards and most of the time F8 is boot sequence settings.

Try F12, if it's not then it's disabled somewhere.


After poking around for a bit I found this:

The firmware hub on the motherboard stores the Setup utility. When you start up the computer, the system provides you with the opportunity to run this probram. Press DEL during the POST to enter the Setup utility; otherwise, POST continues with its test routines.

--ASUS P5MT-M User Manual, Section 4-2 Paragraph 3

It seems DEL is the correct key. I can't find anywhere that would disable it. The only physical jumper that would affect CMOS on your motherboard is the clock reset/master reset.

If there's a splash screen, it may be hiding your options, press TAB at the splash screen then press DEL.

There may be a time delay in your monitor that does not allow you to see the options, do you press DEL to enter CMOS even if the monitor is off?

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How could it be disabled? And how could I re-enable it? – Giffyguy Oct 6 '09 at 20:20
up vote 1 down vote accepted

The problem is that the BIOS waits for the RAID adapter to initialize before it lets you into the CMOS configuration. The RAID card currently won't initialize successfully, but hangs indefinitely, leaving no time for the BIOS to finish initializing and allow the CMOS configuration to be accessed.

Physically removing the RAID adapter from the PCIe slot and re-booting allows the BIOS to finish initializing completely and prompt for the usual access/configuration options.

(In my case, it told me that my CMOS checksum failed and that I needed to either load the default CMOS settings or configure my CMOS manually. I assume the checksum failed due to the fact that I had upgraded the BIOS to a newer version without refreshing the CMOS. It seems that thedude's advice was true in the end - although not the cause of the initial problem.)

I didn't mention my RAID adapter in the initial question because I had no idea it was relevant.
For this I apologize to SU.

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You can try pressing the Pause button and pause the start up and see if it gives you more info. This has helped me before trying to see the amount of RAM or the size of a RAID disk.

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I did try this a few times, actually. It halts the boot sequence so you can read what's on the screen, but it still won't allow me to get into the CMOS configuration. – Giffyguy Oct 7 '09 at 21:45

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