Computer restarts or shuts down by itself: four causes, cheapest first
Whether the machine reboots or goes dark is the most useful diagnostic detail you can give anyone. The two patterns point at different hardware, and one of them is a warning worth acting on quickly.
Shutdowns that get more frequent
are usually a power supply or a thermal fault getting worse. They rarely fix themselves, and the next stage is often a machine that will not start at all.
- Diagnosis is $49 and comes off the bill when you go ahead with the repair.
- Thermal service, cleaning and re-pasting are quoted after inspection.
- A failing drive is checked first on any machine that has been restarting, before data is at risk.
Restart and shutdown are different clues
A machine that reboots on its own is usually being reset by a fault it survived. A machine that goes dark instantly, with no blue screen and no warning, is being switched off by a protection circuit or losing power. Treat them as separate problems, because they have different causes.
- Instant black shutdown, no blue screen: thermal protection doing its job, or a power supply that cannot hold its rails under load.
- Restart with a blue screen that flashes too fast to read: a driver, failing memory, or a drive error.
- Restart with no blue screen at all, most often under load: power delivery, or an unstable overclock.
- Restart at idle, occasionally: often memory, sometimes a driver or a failing board.
Heat first, because it is the cheapest fix
Dust mats between the fan and the heatsink reduce airflow year after year, and factory thermal paste dries out in three to four years. The result is a processor that hits its thermal limit and throttles, then eventually shuts the machine down to protect itself.
A thermal service is a teardown, a proper clean of the fan and fins, fresh paste and new thermal pads where they have gone hard, with temperatures measured before and after. It is the least expensive cause to rule out and, on a machine that has never been serviced, the most common one.
Why timing matters
If the shutdowns started in summer, or after the fan got noticeably louder, treat it as thermal until proven otherwise and stop running anything demanding until it is checked.
Power supply second
A desktop power supply degrades quietly. Capacitors age, the unit delivers less than it did, and the first symptom is a restart or shutdown exactly when the graphics card asks for a burst of power. That is why the fault often appears during a game and never during office work.
Age, brand and previous load all matter, and so does sizing: a unit that was borderline when it was new has no margin now. A supply that fails outright can take the board and drives with it, which is why this is not a fault to run with.
Memory and drivers third
Bad memory produces blue screens, and testing it means running a proper memory test rather than reading error logs. It also means checking the memory is seated, that a matched pair is in the right slots, and whether an overclocking profile is doing something the machine cannot sustain.
Driver faults show up in the dump files, which is what the diagnostic reads: the stop code names the component that failed, and that turns a guessing game into one or two specific tests.
The diagnostic order, and what it produces
The machine is checked in a fixed order, because the cheapest explanations are also the most common: temperatures and cooling, then the power supply, then memory, then storage health, then the dump files and driver history. Nothing is replaced until a test points at it.
You end up with either a repair and a price, or an honest assessment that the machine is not worth the parts. Either way the fault is named, and the $49 diagnostic comes off the bill if you go ahead.
What it costs
The $49 diagnostic is waived if you proceed. Thermal service and cleaning are quoted once the machine is open, and a replacement power supply is quoted with the part price before it is ordered.
Why MTech Repair
A repair bench, not a mall kiosk.
Diagnostics happen in front of you, parts grades are named before they are ordered, and every device leaves with a tested result rather than a promise.
- Quote first
- You approve the exact price before a single screw comes out.
- 90-day warranty
- Workmanship is covered, on both local and mail-in repairs.
- Same-day bench
- Most phone repairs are finished while you wait, 45 to 60 minutes.
- Tracked both ways
- Mail-in repairs ship insured and tracked in both directions.
Common questions
What people ask before booking this repair
Get it fixed
Two ways to hand it over, one standard of work.
Drop off or meet up around Flemington for same-day service, or mail the device in from anywhere in the US. Computers are tested before and after, and you hear from a technician, not a call center.
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