You press the power button and… nothing. Or the fans spin but the screen stays black. Or it starts, cuts out, and starts again. It's one of the most stressful things a computer can do, but it's also one of the most common jobs on our bench — and a surprising number of “dead” PCs come back to life with a check that takes thirty seconds.
First, work out which of these three you're seeing, because each points somewhere different:
- Completely dead — no lights, no fans, no sound at all. Usually a power problem: the outlet, the cable, the power supply, or (on laptops) the charger or charging port.
- Lights and fans, but no picture — the PC has power but isn't finishing its start-up checks. Often memory, the graphics connection, or simply the monitor.
- Turns on, then off again (or loops) — something is failing the moment it's under load: power supply, overheating, a short, or a component that isn't seated properly.
Stop now if any of these apply
A burning smell, a pop or spark from the power supply, a recent liquid spill, or a laptop whose case or trackpad is bulging (a swelling battery). Unplug it at the wall and don't keep trying to power it on — that's how a one-part repair becomes a three-part repair. Book it in instead. And never open a power supply unit itself: its capacitors can hold a dangerous charge long after it's unplugged.
The checks, in order
Check the power, end to end
It sounds obvious, but it catches people out constantly. Plug something else into the same outlet to prove it works. If you're on a power board, check its switch and try the wall directly — boards with surge protection can fail silently after a storm. Push the cable firmly into the back of the PC, and on desktops check the I/O switch on the power supply at the back is set to “I”.
Desktops use the same kettle-style cable as many monitors and printers, so swapping in a known-good one is a free test.
Drain the leftover power
Unplug the PC (or the laptop charger), then hold the power button down for 20–30 seconds. This drains residual charge and clears a “stuck” power state that can stop a machine responding at all. Plug back in and try again.
On a laptop, also check the charger: most have a light on the brick or by the charging port. No light, or a light that flickers when you wiggle the plug, points at the charger or the charging port — not the laptop itself.
Fans spin but no picture? Rule out the screen
Make sure the monitor is on and set to the right input (HDMI 1, DisplayPort and so on). If your desktop has a separate graphics card, the screen cable must go into the graphics card's ports lower down the back — not the ports near the USB sockets, which usually do nothing when a graphics card is installed.
Try a different cable or another screen (a TV works). On a laptop, plug in an external monitor: if that shows a picture, the laptop's own screen or its cable is the problem.
Listen for beeps, look for lights
Many desktops beep, and many motherboards have small labelled LEDs — CPU, DRAM, VGA, BOOT — that stay lit on whichever part failed its start-up check. A pattern of beeps or a lit DRAM light is the motherboard telling you exactly where to look. Look up the pattern for your motherboard model in its manual.
Undo anything that changed recently
New RAM, a new graphics card, a moved PC, a Windows or BIOS update, a storm the night before? The last thing that changed is the first thing to suspect. Put the old part back, or unplug anything newly connected — including USB devices, which can occasionally stop a PC from starting.
Reseat the memory (desktops)
Switch off at the wall, hold the power button to drain it, and open the side panel. Touch the metal case to discharge static. Open the clips on the RAM slots, lift the sticks out, and press each back in firmly until both clips snap shut — it takes more force than people expect. If you have two sticks, try starting with just one, then the other.
Moving a PC, even just across a room, can be enough to unseat a stick. A lit DRAM LED makes this the first thing to try.
Check the internal power cables
While the side is off, check the big 24-pin connector on the motherboard, the 8-pin CPU connector near the top-left of the board, and the power cables into the graphics card are all fully clipped in. If the case was recently moved or cleaned, also check the small front-panel wires that connect the power button to the motherboard.
What it usually turns out to be
Once the simple checks are done, a PC that still won't start usually has one failed part. On the bench we test each one in isolation with known-good parts, which is the only reliable way to tell a dead power supply from a dead motherboard — they can look identical from the outside.
- Power supply — the most common culprit for a completely dead desktop, especially after a storm or power outage.
- Memory — a failed or unseated stick is a classic cause of “fans but no picture”.
- Laptop charger or charging port — worn ports are common on laptops that get carried around a lot.
- Motherboard — less common, and the one to confirm properly before paying for it.
Diagnostics start at $80.00, and you get an itemised quote before we replace anything. Your drive is almost never affected by a power fault, so your files are usually safe — we'll check that first either way.
Still no signs of life?
Bring it in and we'll find the dead part on the bench — tested, not guessed, with a quote before any work starts.
Mount Evelyn bench · drop-off or pickup across the Yarra Ranges · 0494 434 956