A desktop that will not turn on has lost its mains supply, lost the link between the power supply and the motherboard, or is being stopped by a protection circuit. Work from the wall socket inwards: socket, cable, surge strip, the switch on the power supply, the case button, and only then the power supply and motherboard. A few minutes of outside checks often settle the question before you open anything.
What does your PC actually do when you press the button?
The exact behaviour at the moment you press the power button is the best clue you have. Before you touch a screwdriver, note whether you see any light, hear any fan movement, or get a sound. The table below maps what you observe to the part of the machine that deserves suspicion first.
| What you see | Where to look first |
|---|---|
| Nothing at all: no light, no fan, no sound | Wall socket, power cable, surge strip or UPS, switch on the PSU, then the PSU itself |
| Small light on the motherboard, but the button does nothing | Case power button, front-panel connector, or a PSU that is not responding to the start signal |
| Fans twitch or spin for a second, then stop | A short circuit, a missing CPU power cable, badly seated RAM, or the PSU protecting itself |
| Starts, then shuts down within seconds | CPU cooler not making contact, severe overheating, or an overloaded or weak PSU |
| Restarts again and again | RAM, corrupted BIOS settings, or a flaky PSU |
| Fans and lights run, but the screen stays black | Not a power fault, so follow a no-display or beep-code guide instead |
That last row catches many people out. If the machine is clearly powered but shows nothing, the problem has moved on from power to memory, graphics or the CPU, and a different checklist applies.
Which outside checks should come before you open the case?
Start outside the cabinet, because power faults in Indian homes and offices are very often upstream of the PC. Voltage dips, power cuts, tripped breakers and tired surge strips all produce a computer that appears dead. Work through these in order and test after each one.
- Try a different wall socket. Plug in a lamp or phone charger first to prove the socket is live. Check that the breaker or ELCB has not tripped, particularly after a storm or a power cut.
- Bypass the extension board and UPS. Connect the PC cable straight to the wall. A UPS with an exhausted battery or a failed inverter stage can refuse to pass power through, and cheap extension boards fail internally.
- Swap the power cable. The kettle-style lead is a cheap, common failure. Any monitor or kettle cable with the same connector is a quick test.
- Check the switch on the back of the PSU. It must be set to I, not O. Children, cleaning and cable-pulling flip it more often than you would expect.
- Check the voltage selector, if there is one. Some older power supplies have a small red 115V/230V slider. Indian mains is 230V. If it was left on 115V, stop and do not keep trying, because the supply may already be damaged.
- Unplug everything else. Remove USB devices, printers and extra drives. A shorted USB device or a faulty front-panel port can stop a system from starting.
How do you check inside the case safely?
Switch off at the wall, unplug the power cable, then press and hold the case power button for about ten seconds to drain stored charge. Touch bare metal on the case before reaching in. Take a quick phone photo of the cabling so you can put everything back exactly as it was.
Cables, lights and the front panel
Press the large 24-pin connector and the 4-pin or 8-pin CPU power connector firmly into the motherboard until each latch clicks. A cable that is almost seated produces exactly the "dead" behaviour you are chasing. Plug the PC back in and look for a tiny standby LED on the motherboard; many boards show one whenever the PSU is delivering its standby voltage. Its presence tells you the PSU is at least partly alive.
If the LED glows but the button does nothing, the button circuit is the next suspect. The two pins labelled PWR_SW (check the board's manual) can be briefly bridged with the tip of a screwdriver. If the system starts, the case button or its cable is faulty and the rest of the machine is fine.
Strip it back to a minimum
If it still fails, remove the graphics card (if the CPU has integrated graphics), disconnect all drives, and leave a single RAM stick in the slot the manual recommends, usually the one furthest from the CPU. Reseat that stick. Look for bulging or leaking capacitors, scorched marks or a burnt smell, and check the cooler is actually clamped to the CPU. A stray motherboard standoff under the board can also short it, which is worth ruling out if you recently rebuilt the PC.
As a last low-risk step, remove the coin cell battery for a few minutes with the PC unplugged to reset the BIOS settings. A dead or very weak CMOS battery usually only causes lost time and settings, but a corrupted setting can occasionally stop a board from starting.
Is the power supply dead? The paperclip test, and its limits
Bridging the green start wire to a black ground wire on the 24-pin connector makes a PSU switch on without a motherboard, and if its fan spins, the PSU is at least not completely dead. That result proves very little, though. A supply can spin its fan with no load and still collapse the moment the system draws real power.
If you try it, unplug the PSU from every component first, switch off at the wall before touching the connector, and never open the PSU casing. The capacitors inside hold a dangerous charge long after unplugging. A borrowed known-good PSU, or a dedicated PSU tester, gives far more reliable evidence than a paperclip. Our guide to failing power supply signs explains what a weakening PSU looks like before it dies outright.
Branded pre-built PCs often use non-standard connectors and compact power supplies, so you cannot always swap in a standard ATX unit. In that case the safe route is a technician who can match the exact part, which is how the power supply replacement service works.
When is the motherboard to blame, and what does it cost?
If a known-good power supply, a minimal setup and the front-panel test all give the same dead result, the motherboard moves to the top of the list. Signs include no standby LED despite a good PSU, visible burn marks, swollen capacitors, or a smell of overheated components. A failed CPU is possible too, though much rarer than a board or PSU fault.
Costs depend on which part failed. Xigox's indicative price list shows PSU replacement from ₹1,500 to ₹2,500 for a 450W unit, ₹3,000 to ₹5,000 for 650W, and ₹5,000 to ₹8,000 for 850W and above. Motherboard repair is listed from ₹2,999 to ₹8,999 depending on model and fault. Your hard disk or SSD is a separate component, so your files are normally safe whichever part has failed.
To cut the risk of a repeat, plug the PC into a decent surge-protected socket or UPS. We cover the options in our guide to surge protection and UPS buying in Mumbai.
Frequently asked questions
Why does my PC turn on for a second and then shut off?
The power supply or motherboard is detecting a fault and cutting power. Common triggers are a CPU cooler that is loose or missing its contact, a short from a misplaced standoff, badly seated RAM, or an overloaded PSU. Disconnect extras and test with minimal parts to isolate it.
Can a dead CMOS battery stop a PC from turning on?
Usually it does not. The battery only keeps the clock and BIOS settings. A dead one typically causes wrong date and time or a boot error. On some boards, corrupted settings from a depleted battery can stop startup, which is why clearing CMOS is a reasonable test.
Will I lose my files if the power supply has died?
Almost never. A PSU failure does not touch the storage drive, and the data stays on the disk. The exception is a surge strong enough to damage other components, which is why a quick inspection of the drive is worth doing after a bad power event.
Is it safe to replace a PSU myself?
On a standard ATX tower it is a manageable job if you match the connectors and choose enough wattage for the graphics card. On branded pre-built desktops with proprietary power supplies, it is better left to a technician.
If your desktop is still dead after these checks, Xigox can collect it from your door, diagnose the fault and quote in writing before any work starts. The ₹350 inspection fee is refunded if you go ahead with the repair. See the PC not turning on service, read our beep code guide if you hear sounds, check the price list, or book a free pickup. A broken board may also be repairable, as explained under desktop motherboard repair.
