Hi there, I have had my pc for about 5 years and have hardly had any problems. I shut down normally but recently it is taking me 6-7 attempts to switch it back on again. when I press the switch everything flickers, keyboard, screen, hardrive but then goes off, it then wont let me switch on again so I have to turn off at the back, unplug from the socket and try again, it takes me 6-7 attempts before it actually switches on.

Any ideas?

Could be several things. Most likley is the PSU (power supply) is bust.

Could also be overheating problems due to buildup of dust.

Or any other piece of hardware could be dying. It is quite old, it happens.

I vote for the power supply. If yours is 5 years old, it is time to replace it anyway. If the interior of the computer has not been kept clean of heat-trapping dust, and your problem is the result of overheating, then sadly, the damage has already been done if the symptoms are seen at startup, presumably after the computer has cooled down again. Either way, heat is the bane of all electronics so if something on the motherboard or inside the computer failed, it would be because the component could not take the abuse from excessive heat and fried, or because the component was 5 years old, aged and weakened, could no longer support a normal load, then fried. rpmorrow is right - it happens.

The good thing about power supplies is the ATX standard that governs them. Every power supply designed for ATX cases and ATX motherboards (which is about 99% of all made in the last 10 - 12 years - unless this is an old Dell ) will fit your old case (if not a laptop or mini-PC), and connect to your legacy (older) devices (perhaps with supplied adapters), as well as newer devices, such as SATA drives and graphics cards. And since ATX is likely to be the standard for many years to come, if you buy wisely now, it will carry you through at least one motherboard/CPU/RAM upgrade, and the ever more demanding graphics power requirements of today's, and tomorrow's graphics cards. Note that a good graphics card can easily demand more power than the CPU.

Also, replacing the PSU is a lot easier than replacing the motherboard. It is not likely you can find the exact same model number AND revision number to support your CPU and RAM, and NOT cause Windows to choke at first boot at seeing a bunch of new hardware devices suddenly, probably triggering a re-authentication if lucky, fresh Windows install if not.

If you need a new motherboard, then it is time for a complete motherboard/CPU/RAM/Graphics upgrade, which will require a new PSU anyway, then you might as well get new SATA hard drives too. And Vista. You can keep your keyboard, mouse, and speakers, and monitor.

Let's hope it is just the PSU, but in reality, I expect computers to last 5 years, and plan for that, even though I have a couple BOINC crunchers running 24/7/365 at 100% that are over 7 years old.

Below are my canned texts on testing PSUs, and selecting the right new one.

I use a FrozenCPU Ultimate PSU Tester for power supply (PSU) testing when I am away from home. It is not as good as a qualified technician testing the PSU under a "true" (realistic) load with an oscilloscope or power analyzer, but close. The advantage of this model is that it has an LCD readout of the voltage. With an actual voltage readout, you can better detect a "failing" PSU, or one barely within specified tolerances. Lesser models use LEDs to indicate the voltage is just within some "range". These are less informative, considerably cheaper, but still useful for detecting PSUs that have already "failed". Newegg has several testers to choose from. All these testers contain a "dummy load" to fool the PSU into thinking it is connected to a motherboard, and therefore allows the PSU to power on, if able, without being attached to a motherboard - great for testing fans, but again, not a true load. Alternatively, you can swap out the PSU with a known good one that meets the computer's power requirements.

I do not recommend using a multimeter to test power supplies. To do it properly, that is, under a realistic load, the voltages on all the pins must be measured while the PSU is attached to the motherboard and the computer powered on. This then requires poking (with some considerable force) two, hard and sharp, highly conductive, meter probes into the heart of the computer. One tiny slip can destroy the motherboard, and everything plugged into it.

Use the eXtreme PSU Calculator Lite to determine your power supply unit (PSU) requirements. Plug in all the hardware you think you might have in 2 or 3 years (extra drives, bigger or 2nd video card, more RAM, etc.). Be sure to read and heed the notes at the bottom of the page. I recommend setting Capacitor Aging to 30%, and if you participate in distributive computing projects (e.g. BOINC or Folding@Home), I recommend setting TDP to 100%. Research your video card and pay particular attention to the power supply requirements for your card listed on your video card maker's website. If not listed, check a comparable card (same graphics engine and RAM) from a different maker. The key specifications, in order of importance are:

1. Current (amperage or amps) on the +12V rail,
2. Efficiency,
3. Total wattage.

Then look for power supply brands listed under the "Good" column of PC Mechanic's PSU Reference List. Ensure the supplied amperage on the +12V rails of your chosen PSU meets the requirements of your video card. Don't try to save a few dollars by getting a cheap supply. Digital electronics, including CPUs, RAM, and today's advanced graphics cards, need clean, stable power. A good, well chosen supply will provide years of service and upgrade wiggle room. I strongly recommend you pick a supply with an efficiency rating equal to, or greater than 80%. Look for the 80 Plus - EnergyStar Compliant label. And don't forget to budget for a good UPS with AVR (automatic voltage regulation).