How To: Fix a com­puter that won’t boot

JIM MARTIN re­veals what you should do if your PC won’t start

Tech Advisor - - How To -

1. Check the power sup­ply

Lap­tops This is one of the most com­mon prob­lems. There are var­i­ous things that can go wrong, from us­ing the wrong lap­top power sup­ply (de­liv­er­ing the wrong voltate) to a blown fuse in the plug.

It might be that your power sup­ply has sim­ply failed. First, make sure the bat­tery has some charge.

If you’re not sure, and there’s no power in­di­ca­tor on the bat­tery it­self, then re­move it en­tirely and just use the mains charger.

Dou­ble-check, too, that the charger is the right one for your lap­top. Many lap­tops – es­pe­cially from the same man­u­fac­turer – use the same size plug, and if you own more than one, it’s not too dif­fi­cult to plug in the wrong power sup­ply, which might pro­vide a dif­fer­ent volt­age or not enough cur­rent.

Other gad­gets may also use the same tips, such as a bat­tery pow­ered speaker, and are un­likely to use the same volt­age as your lap­top, which typ­i­cally re­quires 16- to 20V.

Se­condly, check the fuse in the plug. Use a screw­driver to re­move the fuse and in­stall one that’s known to be good. If you have a spare power ca­ble that will plug into your power sup­ply, this is a much quicker swap to test that it isn’t the fuse at fault.

Check over the wire it­self, as power sup­plies get beaten up, es­pe­cially if you carry them ev­ery­where. Weak points are at the ends where it joins the black brick and at the plug which con­nects to the lap­top. If you can see the coloured wires in­side the black outer pro­tec­tion, it could be time to buy a new PSU. PCs PC power sup­plies can also be prob­lem­atic. Few peo­ple have a spare they can in­stall and test, so the first check is the fuse in the plug. There’s also a fuse in­side the PSU it­self, but it will re­quire you to re­move it from your PC and then re­move the metal case to check if that’s the prob­lem.

One of the most com­mon PC power sup­ply is­sues is that the PC will turn off un­ex­pect­edly rather than fail to boot up at all. If the LED is on show­ing that power is reach­ing it, make sure your power but­ton is prop­erly con­nected and work­ing. You can short the ap­pro­pri­ate mother­board pins to­gether (check which ones in your mother­board man­ual) to elim­i­nate the power but­ton from the equa­tion.

2. Check the screen

Lap­tops Try dis­con­nect­ing any ex­ter­nal dis­plays in­clud­ing pro­jec­tors and mon­i­tors to make sure they’re not stop­ping your lap­top from boot­ing into Win­dows.

If your com­puter’s power LED lights up and you can hear the hard disk or fan(s) whirring, but there’s no im­age on the screen, then make the room dark and check that there isn’t a very faint im­age on the screen.

It’s easy to think a lap­top isn’t boot­ing when in fact, it’s the screen that’s the prob­lem.

If there is a faint im­age – maybe the Win­dows lo­gon screen – then it’s likely that your screen’s in­verter has failed. This com­po­nent changes the direct cur­rent (DC) com­ing from the bat­tery or power sup­ply to an al­ter­nat­ing cur­rent re­quired by the screen.

Re­plac­ing an in­verter isn’t too dif­fi­cult if you’re handy with a screw­driver, but it’s cru­cial you buy the right re­place­ment part. As in­vert­ers aren’t ex­actly cheap, you can’t af­ford to get it wrong.

If your lap­top ap­pears to be boot­ing fine, but there’s no im­age at all, the LCD panel could be at fault. Re­plac­ing a lap­top screen is pos­si­ble, but dif­fi­cult, and

screens can also be costly. If it’s an older lap­top, it’s worth con­sid­er­ing buy­ing a new one. PCs There isn’t much you can do to fix a bro­ken PC mon­i­tor, but it’s easy – or eas­ier – to swap the power lead and video ca­ble or even the whole mon­i­tor to see if that’s the rea­son your PC won’t boot.

3. Re­move any USB drives or mem­ory cards

As­sum­ing ev­ery­thing is okay with the power sup­ply and screen, your com­puter may be get­ting stuck be­fore it loads Win­dows. A clas­sic cul­prit here is a USB drive or mem­ory card left in­serted into a USB port or card

reader. Typ­i­cally you’ll see an er­ror mes­sage such as “Op­er­at­ing sys­tem not found” which can lead to un­nec­es­sary panic.

For the ma­jor­ity of the time, it means the BIOS is set to try boot­ing from re­mov­able stor­age drives (in­clud­ing cards) be­fore the in­ter­nal hard drive.

It could also be a disc left in the DVD or Blu-ray drive, so check those too.

4. Try a res­cue disc

If you’re see­ing dif­fer­ent er­ror mes­sages, or there aren’t any cards, ex­ter­nal drives or discs caus­ing the prob­lem, try us­ing a res­cue disc.

If you have one, the Win­dows DVD can be used, but oth­er­wise you can down­load (us­ing an­other com­puter – ob­vi­ously) a res­cue disc im­age and ei­ther burn it to a CD or DVD, or ex­tract it to a USB flash drive. You can then boot from this and at­tempt to fix the prob­lem with

Win­dows. If a virus is caus­ing the prob­lem, use a res­cue disc from an anti-virus provider as this will in­clude scan­ning tools which can find and re­move the mal­ware.

We’ve a full guide to mak­ing and us­ing a res­cue disc at

5. Boot into safe mode

Even if you can’t boot into Win­dows, you might be able to get into safe mode. Press F8 as your lap­top is start­ing up and you’ll get a menu of­fer­ing to boot into Safe Mode. Here’s how to en­ter safe mode.

If you can en­ter safe mode, you might be able to undo any changes that caused your lap­top or PC to stop boot­ing. You could try unin­stalling any new pro­grams that you re­cently in­stalled, unin­stall a driver that was re­cently up­dated, or cre­ate a new user ac­count if the ac­count is cor­rupt.

We’ve a more de­tailed guide on how to fix a cor­rupt user pro­file at­wk3bhh.

If you see an op­tion to re­pair your com­puter, try this, but you will al­most cer­tainly need your Win­dows CD for this to work.

6. Check for faulty or in­com­pat­i­ble hard­ware

If you’ve just in­stalled some new mem­ory or an­other piece of hard­ware, it might be pre­vent­ing your com­puter from boot­ing. Re­move it (re­in­stalling the old mem­ory if nec­es­sary) and try again.

If your mother­board has a LED read­out show­ing POST codes, search the man­ual or on­line to find out what the code shown means. Of­ten it can be tricky to get a newly built PC to boot. The best tip here is

to dis­con­nect ev­ery­thing ex­cept the bare min­i­mum needed to boot to the BIOS: • Mother­board • CPU (with heat sink at­tached) • Graph­ics card (if there’s a graph­ics out­put on the mother­board, re­move any plug-in graph­ics cards) • One stick of mem­ory (re­move any oth­ers, and leave the sin­gle stick in slot 0 or whichever the man­ual rec­om­mends) • Power sup­ply • Mon­i­tor

All other hard­ware is un­nec­es­sary: you don’t need a hard drive, op­ti­cal drive or any other com­po­nents for the PC to start. Com­mon rea­sons why a new PC won’t boot are:

• Power leads im­prop­erly at­tached to mother­board. If your board has an ex­tra 12V socket near the CPU, en­sure the cor­rect lead from the power sup­ply is at­tached in ad­di­tion to the large 24-pin ATX con­nec­tor. • Com­po­nents not in­stalled or seated prop­erly. Re­move mem­ory, graph­ics card and CPU and re­in­stall, check­ing for any bent pins on the CPU and CPU socket. • Power but­ton wires con­nected to wrong pins on mother­board. • Power ca­bles not at­tached to graph­ics card. En­sure PCI-E power leads are cor­rectly con­nected if re­quired by your GPU. • Hard drive con­nected to the wrong SATA port. En­sure the pri­mary drive is at­tached to a SATA port driven by the mother­board chipset, and not a sep­a­rate con­troller.

Some­times the rea­son a PC won’t boot is be­cause hard­ware fails and there’s no easy fix. Hard drives are a com­mon is­sue. If you can hear a reg­u­lar click­ing, or the drive spin­ning up and the pow­er­ing down over and over, th­ese are signs that it’s bro­ken. Oc­ca­sion­ally, peo­ple have found that re­mov­ing the drive and putting it in the freezer for a cou­ple of hours (in a freezer bag) does the trick. How­ever, this is usu­ally a tem­po­rary fix and you should have a sec­ond drive on hand to quickly back up or copy any files off the drive that you need.

If you can’t get the drive go­ing again, it’s time to start afresh with a new hard drive. Let’s hope you have a re­cent backup of your im­por­tant files.

Credit: iS­tock

Credit: IDG

Credit: iS­tock

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