Computer wan't turn on

If your surge protector or power strip is under your desk, check to make sure a wandering toe didn't turn it off. If the cord appears to be fine and the socket works, try replacing the power cord or, in a laptop, the AC adapter. You may have to buy one specific to your model. The problem could be with the power supply.

• Check that the PSU is switched to ‘1’ (on) and plugged into the wall – yes, really.
• Double-check that the outlet is good (or try another).
• Check all power connections (PSU-side and board-side).
• Reseat memory and VGA.
• Reset / clear CMOS.

The below sections will walk through each of these individual steps. If these steps don’t sound quite right for your issue – or you’ve exhausted them and need more in-depth testing – our next troubleshooting guide will cover part swapping and issue or defect analysis.

POWER PROVISION

We’re just ruling out the obvious with this one. Make sure that the power supply is connected to the wall with an appropriate power cable. Most PSUs use a standard power cable, but some high-wattage supplies (like the NZXT Hale v2) will use 10A cables. Use the cable that was provided with the PSU for assurance.

Flip the PSU switch to the correct ‘1’ (on) position. If it’s already there, toggle off, wait a few seconds, then back on. You will sometimes hear a ‘click’ that lets you know the components are active.

If it’s still no good, just to make sure we eliminate easiest tests first, try a different power outlet. If the power of the system is excessive – like in multi-GPU computers – you could blow a breaker by exceeding the standard US ~1500W supply. Testing high-wattage PCs on a separate circuit from other high-wattage PCs is encouraged.

POWER CONNECTION CHECKLIST

Follow this checklist for power connectivity. Note that data cables, like SATA or U.2, and even GPU power cables are not necessary to get the system simply to boot. You’ll obviously want the cables for the video card connected, but the absence thereof will not prevent a boot (screen will display a warning to connect PCI-e power cables).

• 24-pin power located near RAM. Ensure that the clip lines-up with the clip on the socket. There is generally only one way to plug these headers in, but a builder could force a backwards connection with enough force (part of our “if it doesn’t go in easily, stop” rule).
• 4/8-pin power near the CPU. This is the EPS 12V supply and is required for boot and CPU power; in our experience, it is also the most commonly overlooked. Almost all motherboards use 8-pin headers for this. Some ultra-budget, mainstream-targeted boards will use 4-pin headers. High-end OC boards occasionally offer optional, additional sockets (upwards of 16 pins) for high overclocks. At this point in the process, you’ve not booted yet and therefore have no overclock – these are not necessary unless the board dictates their connection.
• VGA power connectors for the video card.
• SATA, U.2, and data cables are not needed, but may as well be plugged-in at this point. We will ditch them if we have to go barebones (later in the process).
• PWR_SW connector for the case to the motherboard (this is what makes the power button work).

Next, check that all headers for all cables connected to and fully seated within any modular receptacles on the power supply. You an apply a little bit of force here, just make sure it’s seated in the correct orientation and that the clips are socketed.

Attempt a boot.

If it’s still no good, let’s try the next part:

JUMP-START WITH A SCREWDRIVER

Just to rule-out the possibility that the PWR_SW cable is damaged or defective, we can easily jump-start the system by bridging the PWR_SW contacts through a screwdriver. This is trivial and a useful skill to have.

• Disconnect PWR_SW connector from the motherboard.
• Using a screwdriver, bridge the PWR_SW pins on the motherboard. This is done by using a fat enough screwdriver that the metal tip forms a physical “bridge” between the pins, through which electricity will flow.
• Remove the screwdriver immediately after start.
• The system should power-on if all is well.

RESEAT MEMORY & VGA

If there’s still no video or a failed POST (power-on self-test), it’s worth checking memory and video card seating. If installed improperly or not fully seated (or oxidized from a lack of use over a long period of time), reseating the RAM and VGA is a useful troubleshooting tactic.

To do this, simply remove and reinstall each device per our earlier instruction. Make sure an audible ‘click’ is emitted once the memory clamps and PCI-e clamp lock into the devices. Avoid re-installing the CPU at this time. That is almost never the issue (as long as it was installed properly to begin with) and is the most difficult to re-mount.

CLEAR CMOS BATTERY

All of the motherboard’s configurable UEFI or BIOS information is stored on the CMOS battery, a round, silver battery that’s normally positioned near between PCI-e slots (on an ATX board) or near the video card. Some mini-ITX boards will mount the CMOS battery vertically to save space.

It is possible – and has happened to us regularly – that settings in BIOS are somehow preventing a proper boot. This is the nature of introducing the motherboard to a new CPU and memory. To reset CMOS, the most sure-fire way is to follow these steps:

• Disconnect power from the PSU (to the wall).
• Toggle the PSU off.
• Locate CMOS battery. Depress the tab and pop the battery out.
• Wait 15-30 seconds, then re-insert battery.
• Reconnect power (and VGA, if it was in the way) and toggle PSU on.
• Attempt a boot.

In a continuation of our previous efforts to troubleshoot first-time boot errors upon system build completion, this guide takes more in-depth steps of situation analysis. The prior guide discussed CMOS resets, memory and VGA reseating and re-installation, and power contact checkpoints. For most users, that guide should act as a catch-all for most first-time boot issues – but it won’t resolve all problems.

The next steps require some “un-building” of the system, but will validate that no user error was made during the process of system assembly.

As previously, here’s a bulleted outline prior to more in-depth guidelines:

• Go barebones and strip the system down to only the required components.
• Check for short-circuits between the board and the case.
• Swap parts (where possible) to locate potential defective or DOA components.

Let’s start with the barebones approach, as that’s most likely to root-out easy issues.

GOING BAREBONES ON THE BUILD

When system builders use the word “barebones,” they’re referring to the stripping-down of a system to only its essential components. If one component is blocking the system’s ability to boot, these steps should find that component.

First, determine if your CPU is capable of supporting on-board graphics (and that the motherboard has it to offer – almost all will). If so, the VGA is the first component that can be disconnected from power and removed. Connect any display cables (DVI, HDMI, DisplayPort, etc.) to the motherboard directly. If not, the VGA is required.

The next step has to do with RAM – often the culprit – and the removal thereof. Remove all but one stick of memory (if you only have one stick, check the last section on part swapping). You will need to keep track of which memory sticks have been tested through this process. We will rotate the sticks through to determine if any particular stick is throwing failures.

Disconnect all non-essential cooling (case fans).

Finally, disconnect all storage devices from both their interface (data connection) and power. We should now be running:

• Motherboard + CPU
• CPU Fan
• One stick of RAM
• Internal graphics (if present)

Attempt a boot. Consider resetting CMOS between (see previous guide).

Rotate through RAM until all sticks have been tested. If a particular stick prevents boot, you’ll have to go through the RMA process or return process with the manufacturer or retailer (respectively).

CHECK FOR SHORT-CIRCUIT CONNECTIONS

If, during motherboard installation, the standoff hex screws were improperly installed or left out entirely, the motherboard could very likely be forming a direct short with the case. The motherboard should never contact any other piece of metal directly unless that piece is part of a power or data pin. The board and case should not touch as this would form a bridge and directly short the motherboard.

The bad news first: checking for shorts is a pain, as it requires a complete system uninstall to inspect the standoffs. Check that every relevant mount point (for the board’s form factor) is outfitted with a standoff. Remove any standoffs which do not directly align with screw holes in the motherboard. Note that component weight can cause the motherboard to sag and make contact with the case, even if it’s elevated – that’s why every screw matters. Do not skip screws.

If the VGA is still installed (no IGP), check any aftermarket heatsink brackets or fan mounts / tower fins to ensure that there is no collision between the rear of the VGA and the mount points.

As an aside, it’s also worth replacing (if available as an option) modular power cables with the spares or extras that some PSUs will include.

SWAP PARTS

This step will require a functional, known-good system to use cooperatively as a troubleshooting agent. If neither you nor a friend have spare parts that can be temporarily borrowed from functional systems, check with local PC repair shops. This will save time in the event of individual component failure and avoid unnecessary shipping.

• Start with the PSU. Remain barebones, but swap the PSU (and any connected cables) with a known-good power supply.
• Move to memory: If that’s still no good, swap memory to a different configuration.
• If the VGA is installed (no IGP), do the same for the video card.

If still have that problem just buy new computer.......