Keyboard recognized only at first boot

neone · 13 Jun 2012

Hi everyone, today I built new pc for my brother and encountered a problem.

When I start pc first time (after reconnecting it to power socket), keyboard is recognized and I can see HID Keyboard Device and Standart PS/2 Keyboard in my device manager, but when I restart or shutdown and again start computer, I see only HID Keyboard Device and I also can't use keyboard, it seems like frozen. Num Lock is on, but I can't turn it off and no keys are working.

I am also able to enter bios when keyboard is not recognized, but I can't use it after I'm in bios.
On first boot I can use it in bios.

I noticed that on first boot, when keyboard is recognized, all three lights (num lock, caps lock and scroll lock) are blinking two times: when bios screen is shown and after windows boot screen. When it is not recognized, I don't see second blinking after windows boot screen.

Can anyone help me? It's very annoying problem. Now I am on first boot and able to use keyboard, but if I restart, it becomes useless.

Operating system is Windows 7 Ultimate x86.
Hardware:
Motherboard: Gigabyte GA-78LMT-S2P (updated bios to F5a)
CPU: AMD Athlon II X2 260 3.3Ghz
RAM: Crucial Rendition 2GB DDR3 1600Mhz
Video Card: Gigabyte HD6670 1GB DDR3
PSU: FSP Hexa 400W

TVeblen · 13 Jun 2012

Hello neone. Welcome to the forum.

Is this a wired PS/2 keyboard connected to a PS/2 socket, a USB keyboard, or a wireless keyboard?

neone · 14 Jun 2012

It's a wired PS/2 keyboard connected to PS/2 socket. I also have 2 USB mouses: one wired, one wireless, and they are working perfectly.

This keyboard also works perfectly on other computer.

TVeblen · 14 Jun 2012

If it works on another computer but not on yours then that isolates the problem to the PS/2 socket or the motherboard.

What happens if you use a known good (different) keyboard on your system?

If I understand correctly, this problem occurs on restart at the BIOS level also?
This is important because it basically eliminates the OS from the equation. If it worked in BIOS but not in OS then we would go in a totally different direction.

You could make diagnostic testing easier by disconnecting the hard drive and just work at the BIOS level. You can use the reset button on your case to simulate a restart. You need to see the keyboard work properly in BIOS before anything else.

A "Cold Boot" is what you refer to as "First Start". This is a start from a completely off state.
A "Warm Boot" is what happens when the computer restarts while everything is on and running.

Some of the differences between a "Cold Boot" and a "Warm Boot" is that all of the RAM registers are clean (empty) on a cold boot, but things like IRQ information is retained in a warm boot.
Older motherboards used an actual "read only" CMOS for the BIOS, but newer MBs use a flash memory EEPROM type of chip. This may also be written clean on a cold boot.

So I'm guessing that perhaps the information needed to run the keyboard is being lost in a restart. Here are a couple of things you could check/try:

Test or replace the 3v battery on the motherboard (it is not unheard of to get a defective one in a brand new board)
Double check all of the connections to the motherboard.
Check the BIOS Settings to see if there is a Legacy "Device" Setting and toggle it back and forth to see if it changes anything.
Perform a Clear CMOS (read your manual for instructions)

If none of these things correct the issue you may be looking at an RMA for the motherboard.

neone · 14 Jun 2012

Thanks for info, I'll try.