Your desktop won’t power on — what is actually wrong?
Short answer: If pressing the power button produces no response at all — no fan, no light, no beep — the SMPS (the power supply box inside your computer cabinet) has most likely failed. The SMPS converts 230V AC from the wall into the lower DC voltages the motherboard and components need. Without it, nothing in the desktop receives power. SMPS failure accounts for the majority of “completely dead desktop” cases we diagnose, and replacement costs ₹1,500–₹4,500 depending on wattage — far less than a motherboard or CPU.
The reason this happens in India more often than in cooler climates is straightforward: our power grid delivers frequent cuts and voltage irregularities. Each time electricity returns after a cut, an unregulated spike hits everything plugged into the wall. The SMPS has internal capacitors (small components that store and smooth charge) that absorb these spikes — but only so many of them before a capacitor blows and the unit stops working. Four to five years of regular power cuts is typically all it takes.
How to diagnose a desktop that won’t power on
Step 1: The wall and socket check
Before opening the cabinet, eliminate the obvious. Try a different wall socket — a tripped MCB (Miniature Circuit Breaker, the small switch in your distribution board that trips under overload) can cut power to a single circuit silently. Also check that the power switch on the back of the cabinet (just above where the power cable plugs in) is in the ON position — it is a small rocker switch and is occasionally bumped off during cleaning or moving the machine. If there is a UPS (Uninterruptible Power Supply — a battery backup unit) in the chain, confirm it is charged and outputting power. These three checks take under two minutes and solve perhaps one in ten “dead desktop” calls without any further diagnosis.
Step 2: The paperclip SMPS test
This is the fastest way to determine whether the SMPS itself has failed, without any specialised equipment. Switch off the power at the wall and unplug the machine. Open the side panel of the cabinet. Find the 24-pin ATX connector — the widest flat cable running from the SMPS to the motherboard, usually with a black plastic clip on one side. Unplug it from the motherboard. Take a metal paperclip and bend it into a U shape. Insert one end into the green wire pin (labelled PS_ON, typically at position 16 on the connector) and the other end into any black wire pin (Ground). Plug the SMPS power cable back into the wall and switch it on.
If the fan inside the SMPS spins, the SMPS is alive — the problem is downstream (motherboard, RAM, or a connected drive may be causing a short that prevents startup). If the fan does not spin at all, the SMPS has failed and needs replacement. This test eliminates or confirms the SMPS in under three minutes. Remove the paperclip before reconnecting anything.
Step 3: Identifying downstream causes when the SMPS passes the test
If the SMPS fan runs during the paperclip test but the desktop still will not start normally, the fault is elsewhere. The most common causes are a short circuit caused by a failing hard drive or optical drive drawing too much current (disconnect drives one by one and retry), a faulty RAM stick (remove all RAM, reseat one stick in the first slot and retry), or a failed motherboard power delivery circuit. A desktop that starts without any drives connected but fails with them connected points clearly to one of those drives as the culprit. Motherboard failure is less common but more expensive — this is where a workshop visit pays for itself, because the diagnosis determines whether you are replacing a ₹600 hard drive or a ₹6,000+ motherboard.
Step 4: The India angle — how power cuts kill SMPS capacitors
Indian electricity infrastructure delivers two distinct hazards to desktop power supplies. The first is the cut itself — not harmful on its own. The second is the return spike: when grid power resumes after an outage, the initial current is often irregular, with a brief voltage overshoot. This spike lasts milliseconds, but repeated exposure fatigues the electrolytic capacitors inside the SMPS — components that look like small cylinders and regulate voltage stability. A fatigued capacitor either bulges (visible on inspection) or fails silently by losing capacitance, causing erratic voltages that eventually crash the unit.
The solution is a UPS (Uninterruptible Power Supply) placed between the wall and the desktop. A UPS converts the incoming AC to DC, charges an internal battery, and then re-converts it back to clean AC before delivering it to the desktop. The spike from the grid never reaches the SMPS. A good desktop UPS for a home or office setup (650 VA to 1 kVA) costs ₹2,500–₹5,000. We see repeatedly that desktops on UPS-protected circuits last 8–10 years before SMPS failure, while unprotected machines in the same building fail in 4–5 years. The UPS pays for itself in avoided repairs within two power-cut seasons. A standalone voltage stabilizer (₹1,500–₹3,500) provides partial protection against sustained over- and under-voltage but does not block the return spike the way a UPS does — a UPS is the preferred option. You can also read our guide on desktop auto-shutdown causes which covers related thermal and power issues.
When to call a repair service (and what it costs in India)
When DIY ends
The paperclip test and basic reconnection steps described above are safe for anyone to try. Stop and call a technician if: the SMPS fan runs but the desktop still does not start and you are not comfortable reseating RAM or disconnecting drives; you can smell a burning odour from the cabinet (indicates a component has overheated or shorted and may need cleaning or replacement); you see visible burn marks or bulging capacitors on the SMPS or motherboard; or the desktop trips the MCB in your distribution board every time you switch it on (a short circuit somewhere in the system).
Typical SMPS replacement cost in India
| SMPS Wattage / Use Case | Typical Cost (₹) | Notes |
|---|---|---|
| 400W–500W (home / office desktop) | 1,500 – 2,500 | 80 Plus Bronze recommended |
| 600W–750W (gaming / mid workstation) | 3,000 – 4,500 | Corsair, Cooler Master, Seasonic |
| 800W–1000W (high-end workstation) | 4,500 – 8,000 | Modular cabling preferred |
| Diagnosis (workshop) | Free | No Fix No Fee applies |
Indicative ranges. Part cost confirmed before any work begins. 30-day warranty on replacement SMPS units.
A note from the LRW Engineer Team
The mistake we see most often on desktop repair calls is owners assuming the motherboard or CPU has failed because the machine is completely dead. In reality, a failed SMPS produces exactly the same symptom as a failed motherboard — total silence. Always check the SMPS first. It is the cheapest part to replace and the most frequently the culprit. If you want a free diagnosis before committing to any parts, bring the cabinet to our Secunderabad workshop or WhatsApp us at 7702503336. For laptop power faults (a related but different problem), see our laptop won’t turn on guide. For signs the issue may be deeper than the SMPS, read our motherboard failure signs guide which covers symptom patterns for both laptops and desktops. Our full desktop repair service covers SMPS, motherboard, RAM, storage, and more.