There are many reasons why you would want to test your motherboard without the CPU attached. Essentially, this test would allow you to troubleshoot your motherboard and point to where a certain fault lies.
Testing a motherboard without a CPU is quite simple. You have to make sure that it is connected to the power supply unit and is placed on a safe material. You CAN have the rest of peripherals and components such as RAM and hard disk attached if you wish, but you don’t have to.
You may also have to learn how to jump start your motherboard in the absence of a Power ON switch.
Basically, in the end you should expect to hear beeping sounds or LED flashes from your motherboard.
Below we will talk in detail about how to test motherboard without CPU and also touch base on how to troubleshoot the issues.
Why and Should You Test Your Motherboard without CPU?
There is nothing wrong with testing your motherboard without the CPU, the only thing you have to keep in mind is that the your PC will NOT pass the POST ( Power-On-Self-Test).
You will see nothing displayed on your screen as well because the motherboard does not have an onboard graphics processing unit. If you have a dedicated GPU installed in the PCIe slot, that too wouldn’t work without the CPU.
The only thing that you may observe are beeping sounds, if your motherboard has a beep code speaker, and LED flashes.
Testing if the Motherboard is Dead or Alive
On many occasions it becomes necessary to test if the motherboard is dead or alive.
Imagine you are building your computer and you have just purchased a new motherboard. If there’s a fault in it and if it came DOA (dead on arrival), it may become more problematic to identify the root cause AFTER you are done building your computer.
Hence, many desktop PC builders and gamers prefer to test their new motherboards BEFORE installing the CPU. This is often called the Pre-build bench test.
This is because as motherboards are sensitive components of the computer, they are prone to damage especially due to mishandling from shipping. There also can be a factory error to provide a non-functional motherboard.
This test may also become necessary if your PC has suddenly stopped working. You may want to perform this test to check if your motherboard is working properly.
How to Test Motherboard without CPU?
Here is how you can test the motherboard without a CPU.
1. Unbox For Bench Testing
Bench test is when you test the PC components outside of the case.
First, unbox your motherboard. Next, remove it and set it on a anti-static foam or material found inside the packaging or on a large piece of cardboard. You can even just place the motherboard on the box that it came with.
Do NOT place the motherboard on a bare metallic or conductive surface! Motherboards have a lot of solder points on the bottom. You do not want these points to come in contact with a metallic surface when turned on.
This is the reason why motherboards inside the case sit on standoffs. These lift the motherboard off from the CPU case so that it does not come in contact with the conductive material.
2. Plug in the Power Connectors
You will need to attach 2 power connectors
- 8 Pin for the CPU power connector on the motherboard
- 24 Pin for the motherboard power connector
The layout of your motherboard may differ, but this generally is the location of where you can find the motherboard and the CPU power connectors.
Both the 24 Pin and the 8 Pin cables are provided with the Power Supply Unit.
Note that my Power Supply Unit also came with a spare 4 pin CPU connector for older motherboards and systems.
These days almost all motherboards come with an 8 pin CPU power connector. The 8 pin provides about 280 watts of power to the CPU, while the 4 pin connector only delivers half as much at about 140 watts.
In the very rare instance that you have a very old system, you would use the 4 pin connector for CPU power.
3. Installing Other Components (Optional)
You can have the rest of the components such as RAM, hard disks and the graphics card installed if you wish, however, they won’t be of much use here without the CPU.
So whether you have them on or not would not make a difference. Although I would recommend that you at least have the hard disks unattached to save you from the risk of losing data due to any mishap.
4. Connect PSU to the Wall Socket
Go ahead and connect the Power Supply Unit to the wall socket. Make sure the power supply unit is also placed on a non conductive surface and make sure that you are grounded.
It would also be best to wear plastic slippers/shoes and to wear non-conductive electric gloves.
5. Turn the Motherboard On
If Motherboard is INSIDE the Case:
If your motherboard is inside the case then turning on your motherboard is quite easy.
Basically, you need to find the Power Switch Pins on your motherboard. These are often located on the Front Panel Header.
Once the Power Switch Pin are identified, you can then connect the Power Switch Cable from your Case to these Pins.
You may have to refer to the your motherboard’s manual to find out the information regarding the exact location of the Power On Switch pins.
The following shows the Power On Switch pins’ location for my motherboard:
Once everything is connected, press the ON button on the Case, and you should be good to go.
If Motherboard is OUTSIDE the Case:
Many newer and higher end motherboards have a manual turn on power button located on them. However, if you have an older or a budget motherboard, then you will have to manually turn the motherboard on.
There are two ways you can go about this:
- Using the case’s Power On switch cables
- Manually jump starting the motherboard
Using the Case Power On Switch Cables
This is similar to the process we highlighted above.
Here, you will need to keep your CPU Case close to the motherboard so that the POWER ON SWITCH cables from the Case can reach the pins on the motherboard’s Front Panel Header. Then you can go ahead and simply press the turn on button on the case as you would normally.
Manually Jump Starting the Motherboard
The second option is to manually jump start the motherboard.
You will need a screw driver for this.
Basically you take the screw driver and with it touch the 2 Power Switch pins on the Front Panel Header.
It would be wise to make sure that the screw driver does not touch any other pins here. Hence it is advisable to use a precision or a small flat screw driver here.
What To Expect? – Beeping Sounds and Flashing LEDs
If you test motherboard without CPU, then the first outcome to expect is that NOTHING will be displayed on your screen.
The other outcome to expect is that your motherboard will perhaps flash LEDs, make beeping sounds or both, or even nothing at all.
LED flashes and beeping sounds are essentially codes indicating where the problem lies.
Beeping Sound Codes
If your motherboard does have a speaker, it will make beeping sounds codes to indicate the issue.
The amount of beeps it makes basically would tell your where the problem lies.
- 1 Beep – issues with the memory
- 2 Beeps – issues with the motherboard
- 5 Beeps – issues with the CPU
There is a whole list of beep sound codes. You can learn more about them here. For instance, if you start the motherboard without a CPU but with RAM and other other components installed, you may potentially hear a 5 beep sound code.
If your motherboard DOES not have a built in beep code speaker, then you can invest in a very cheap one and install it yourself.
Also Read: How to Connect Motherboard Internal Speaker? (Beep Code Speaker)
You may also see certain LEDs on your motherboard flash indicating where the problem lies. To understand what these LED flashes mean, you may have to refer to your motherboard’s manual.
Also Read: How to Reset Motherboard?
No Beep Sounds & No LED Light Flash
The final outcome that you may see is literally nothing.
If you hear no beep sounds and no LED flash lights, then do not fret. This still does not indicate that your motherboard is damaged.
Motherboards Without LED or Speaker
Some motherboard do not come with either of the two i.e beep sound code speaker and the LED lights for indicating where the problem lies.
In this situation, I would advice testing the motherboard through fans.
There are two ways you can go about this:
- Connect the Cooler Fan to the CPU_FAN header.
- OR connect the Case Fans to the 3 Pin FAN headers located on the motherboard which are often labelled as SYS_FAN (Note: not all motherboard have FAN headers).
Also Read: How to Connect Fans To Your PC?
In the second method, you are essentially powering the Case Fans through the motherboard instead of the Power Supply Unit. You will obviously need a Case FAN that has the three Pin connector
If the CPU or System Fans turn on, then you can be certain that the motherboard is receiving the power. This can POTENTIALLY indicate that the motherboard is OKAY, unless, of course, if an essential IC or controller is damaged. In that case the motherboard will still be receiving the power but may not start.
In the end if you have made sure that the motherboard is receiving the power, the last thing to do is to actually attach the CPU and test your system.
- How To Tell if CPU is Bad or Dead?
- How To Tell if PCIe Slot is Bad?
- Can I Upgrade My Laptop Processor from i5 to i7?
In this article, I talked in depth about how to test motherboard without CPU. This is an essential step for many PC builders who want to test the components before installing them into the Case.
This test would highlight if and where the problem lies. Testing the motherboard without CPU is a great way of checking if the motherboard is alive or dead particularly when its brand new and you want to check if it came DOA (dead on arrival).
While I reiterate that the procedure is fairly safe, I would advise that you exercise caution especially if you are a PC builder or seeking to be one. This is because any mishandling or error on your side can also damage the motherboard.
Also, when in doubt, it is best to refer to an expert technician instead of fiddling around with the delicate components yourself.
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