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Keyboard/Interface Error No Keyboard Detected : How To Fix

Keyboard/Interface Error No Keyboard Detected : How To Fix Many a times you have seen that your desktop pc reports a keyboard error “Keyboard Interface Error” press F1 to resume during BIOS boot up.This problem is related to the two PS/2 ports situated on the back of the desktop computer for mouse and keyboard.The system delivers the “Keyboard Interface Error” because it is unable to find any PS/2 keyboard on the motherboard.However when you connect a USB keyboard then it will work but you will still see this keyboard error during bios bootup.So,in this tutorial I will show how I realized and fixed the keyboard interface error for PS/2 port.

Basic Terms Used
1.PS/2 Port
2.ATX Power Supply
3.AT/ATX/uATX/EPS are form factor specification of the motherboard.We buy power supply according to this form factor.For example I will buy uATX power supply for a motherboard having uATX form factor.
4.uATX stands for micro ATX.

How To Fix Keyboard Interface Error
The only solid reason that I found which is responsible for this problem is a low power ATX power supply which is incapable of providing sufficient power to the motherboard to function properly.I was using a 200W (W=Watts) power supply on a 400W ASUS motherboard and a 500W GIGABYTE G41-MTS2.This 200W ATX SMPS is not sufficient for my 400W ASUS P5KPL-VM/S and 500W GIGABYTE G41-MTS2 motherboard.That’s why both the motherboards are power hungry since 4 years that’s why I am getting this keyboard error.Now I explain it in detail starting with checking power supply.

Check Computer Power Supply
A computer motherboard needs enough power to run without any problems.For this you need to install a power supply with correct wattage.Motherboards have different form factors like ATX,micro ATX,AT,EPS etc.Mine is micro ATX which uses a 24 pin main power connector and a 12V 4 pin CPU power connector.Check the form factor of your motherboard whether it is AT,ATX,micro ATX(uATX) or EPS before buying a new power supply.Almost every motherboard today has ATX form factor.Check your motherboards’ manual for this.

24 pin atx power connector

Every motherboard manufacturer sets an optimal power limit in Watts for the motherboard which will be enough at which it can run without being power hungry and all its ports receive enough power.A motherboard has 2 dedicated power sources one is the 24 pin ATX power connector which supplies power to rest of the board except the cpu and a 4 pin 12V dedicated power connector for cpu.These two connectors supply the overall current to the motherboard to run at its full.

It is crucial that you check your desktop computer’s motherboard manual for its power requirement and check whether it matches with the power supply installed in your pc.Today desktop computers require at least 350W ATX power supply to operate without malfunctioning.I have GIGABYTE G41-MTS2 and its power requirement is 500W which means I need to install an ATX power supply which have a power output of 500W.At this power I can use all the internal ports and external ports of my pc without any problem.But this motherboard was running on a 200W ATX SMPS with a 20 pin ATX connector and 2 pins are left unused which is not sufficient power to run this motherboard at its full capacity.

Why I Was Getting Keyboard Interface Error
I was getting keyboard interface error due to low power ATX SMPS.This 200W power supply is unable to provide enough current to all the ports and expansion slots of the motherboard.Due to very low power current in the PS/2 ports the system was unable to find the keyboard because the PS/2 port was not working due to very low current in it.But when I used a USB keyboard it worked fine because all USB ports are getting enough power to operate.Voltage at USB end is 5V DC.Look at the PS/2 pinout diagram.

The pin number 4 was not getting enough power to operate due to a weak power supply.

How I Fixed The Keyboard/Interface Error
Firstly I would say if you are running a 400W motherboard on a 200W ATX power supply then you are surely going to encounter this problem.Not only this problem but other internal and external ports may malfunction due to low current.I strongly recommend to upgrade the power supply of your desktop pc according to the motherboard’s form factor and power requirements for correct operation.Check the manual for correct information about motherboard power requirements.

WARNING : Do not open the motherboard if you do not know anything about it because you can get an electric shock and never open the cabinet cover while the system is connected to AC power outlet and computer is running.It is hazardous.

After I realized that the power supply installed in my desktop is incapable for providing sufficient power to the motherboard then I removed some of the peripherals like DVD RAM drive and floppy drive because these two drives are drawing power for no use and are wasting it and I don’t use them more.So I removed their power and data connectors while the system is off and is not connected to AC power outlet.

I connected the power cord and restarted the pc,now it is running with only a mouse and a keyboard.What I see during bios bootup that the keyboard interface error vanished and the PS/2 ports came back to life and are working properly with a PS/2 keyboard because the motherboard is now getting enough power for itself to operate and the power supply is not under heavy load due to a number a devices connected to it,as I already removed the DVD drive and floppy drive.Now the keyboard error doesn’t show up in bios and PS/2 ports works fine.But I will have to upgrade the power supply to at least 400W.

If you are getting keyboard interface error then this might the case with you.However it is not necessary that you may face the same symptom as I am facing but I will strongly recommend you to check for this low power ATX/uATX/EPS power supply symptom before any other.You can follow these tips to fix this keyboard error.

  • The very first and the most important step is to check the ATX/uATX/EPS power supply.It should be at least 350W or more.check your computer’s motherboard manual for correct wattage specification.The power rating of power supply is written on their top cover.
  • If you find that your ATX/uATX/EPS power supply is incapable of providing enough power then try detaching the DVD drives,floppy drives or any other device connected to it for a short time to ensure that the motherboard doesn’t have any problem.If the motherboard is OK then this keyboard error will vanish on next boot up after you removed the two drives because now the motherboard will get enough power.Make sure to remove the power cord from AC power outlet  before opening the cabinet cover and touching the motherboard otherwise you will get an electric shock and motherboard will get a short circuit and may even catch fire.Be careful about this.
  • If possible then upgrade the power supply according to the motherboard’s power specification.A 200W power supply is too low for todays desktop computer.The minimum requirements is 350W.

Some Other Reasons And Misconceptions About Keyboard Interface Error

  • PS/2 Solder Joints Are Loose : Most experts say that the keyboard interface error can occur due to loose PS/2 port solder joints on motherboard.But this is not completely true if your motherboard is of trusted brand like ASUS,Intel or Gigabyte.I checked the solder joints of the PS/2 port and found them okay.These solder joints are created by automatic machines not by human hands and lasts till the life of the motherboard.They won’t get loose on their own.This a very rare case in which solder joints get loose.However if your pc’s power supply is okay then you can take the help of a hardware expert to check the solder joints.
  • Faulty I/O Microcontroller Chip : Most experts also say that keyboard interface error can also occur due to a failed I/O microcontroller chip on the motherboard.This chip is responsible for controlling the input from keyboard and mouse.If this chip fails or burns then your desktop pc will not accept any input even from USB mouse or keyboard.So this is also not true the I/O controller chip has failed if the USB mouse and keyboard works on your desktop pc.
  • No Keyboard Drivers Installed : You don’t need to install any keyboard driver on a windows pc.The driver will be automatically installed when you connect a PS/2 keyboard to the motherboard.

Final Resolution
The keyboard error occurs mostly due to a low power supply which can’t provide enough power to motherboard to operate properly.The PS/2 port requires exactly 5 Volts.If it gets low power then port will malfunction.I upgraded the power supply unit to 400W according to motherboard power specification and uATX form factor.Now both PS/2 ports are working. But also it is not necessary that this is them same case that applies to your motherboard, your computer's may have other hardware problems. So get it checked before buying a new power supply. Also running a computer motherboard on a low power supply will definitely cause it to malfunction.

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