This guide will cover common issues that can prevent a PC from properly powering on. This includes not only issues where the PC shows no signs of power, but also issues where the PC may show signs of power such as fans spinning or case lights turning on but no signal may go through to the motherboard.
When a PC properly starts, it will go through Power on Self Test or POST to check for any hardware related errors that can prevent the PC from working properly. If your system fails to complete the POST process when powering on, it may hang or simply power off. Common issues that can lead to a system failing POST include, but are not limited to:
- Loose power connections (primarily, 12V CPU, 24-pin ATX, or PCIe/GPU Power)
- Issues with a connected USB device or other connected hardware
- Loose or improperly connected hardware (i.e. loose GPU or RAM sticks)
- Defective Hardware (Faulted CPU, GPU, RAM, or Motherboard)
Troubleshooting these issues can be relatively easy, only taking a few minutes with some systems.
Getting Started - Confirm Power
Before checking for POST issues, you first will want to make sure that the PC itself is properly receiving power. Make sure that the power cable to the Power Supply on the rear of the PC is firmly connected and not loose, and that the outlet itself is giving power. If you are using a plug strip or surge protector, confirm that the strip has power before continuing. It is recommended to try an outlet in another room if the PC is showing no signs of power where it is connected normally.
Disconnect any USB or external devices connected to the PC aside from a single monitor and make sure that the Power Switch on the rear of the PC is set to the I position. If your PC has a dedicated Graphics Card or GPU, please make sure that the monitor is connected directly to the GPU and not to the motherboard's output. GPU connections are generally found 3.5 mm below the audio jacks.
With the switch set to the I position and the PC hooked up to a known good power outlet, try starting the PC using the button located at the top of the system. If the PC shows no signs of power, this could be an indicator of a loose power connection, loose hardware connection, or a severe hardware failure.
If the PC does show signs of power and loads properly into Windows, go ahead and shutdown the PC and start reconnecting devices one at a time, testing if the PC is able to power on after each device is connected. This will help isolate if an outside peripheral is the source of the issue.
If the PC does show signs of power, however you do not get a video signal and are unable to get into Windows then this could be an indicator of a further hardware issue.
The following section will cover basic RAM troubleshooting, for a more in-depth guide please check out our main guide here:
The most common reason a PC may not complete post generally comes down to an error with the RAM. Whether this be due to a stick faulting or simply having shaken loose due to the computer vibrating or moving a loose or improperly connected RAM stick is an often overlooked issue.
If your motherboard has debug features, such as a 2-digit code readout or a set of 4 Debug LEDs, you may want to check if there's a lit DRAM LED or a DRAM related code (generally between 40 and 5F) being reported by the motherboard.
For RAM issues, it is recommended to try reseating the RAM in the PC itself. To do this, please check out the embedded video linked below:
If after reseating the RAM your system still does not complete POST, try removing all RAM from the system and testing one stick installed at a time starting with the 4th (furthest right) slot. Be sure that you turn the PC off completely between each reseat. For more information on this process, please check out the guide linked above.
The following section will cover basic GPU troubleshooting. GPU issues are the second most common reason why a system may fail to complete POST and can be caused either by the GPU not receiving enough power or the GPU itself failing and should be the next stage after testing the RAM. For this guide, we will focus specifically on re-seating the connections to the GPU.
Before starting, make sure that the PC is fully powered off and disconnected from wall power. For an overview of how to reseat your GPU, please check out the embedded video linked below:
If re-seating the graphics card and its power connection did not resolve the issue, then there is a chance that the power connection at the Power Supply Unit (PSU) could also be loose. From here, be sure to trace the power cable from the GPU back to the PSU and make sure that this is securely connected. With the power and card connection confirmed, the last thing to check is that the monitor is properly connected to the GPU. It is generally recommended to shutdown your PC when reconnecting the monitor connection to help alleviate any potential detection issues.
Should the PC still not complete POST, the next step we will go into is checking the boot drive.
M.2 Storage Troubleshooting
This guide will assume that your system uses an M.2 NVMe SSD as the primary storage and boot drive within your PC. An M.2 drive being loose or improperly connected can result in a short, causing the PC to refuse to start or not complete POST. As with the previous steps, please check the embedded video link below on how to reseat an M.2 Storage drive:
Please note, some M.2 slots may be blocked by GPU in your system, so it is recommended to check under the GPU for any additional M.2 slots. If your system is still not able to complete POST with the M.2 installed, please try starting the PC with the drive removed to see if you are able to load into the UEFI BIOS.
Power Connection Troubleshooting
The last thing to check in this guide will be the power connections in the system, in particular the most critical connections which will be the 12V CPU Power normally located in the top left corner of the motherboard, as well as the 24-pin ATX Power located along the right edge of the motherboard as shown in the example photo below.
These cables use a locking mechanism to keep them fully secure and in place, so it should be easy to check if the cables are loosely connected. You can also try re-seating these power connections to further confirm if there any issues.
If after checking all of the above hardware the PC is still unable to post, this could be an indicator of a severe hardware problem that may require more advanced troubleshooting. If you have an NZXT BLD PC that is unable to post after following this guide, please reach out to our Customer Support team for further assistance.