Hi all.

Seems i have had no end to troubles latley

I had a powercut yesterday and since then i haven't been able to get my monitor to work, i just get the no signal message.

The PC powers up fine, fans, hdd etc.

So far i have tried a different monitor and 2 different video cards all to no avail.

Any help greatly appreciated

Nick

So far i have tried a different monitor and 2 different video cards all to no avail.

Well, that's not good. You need to start with known good power. Since this is after a power hit, you must consider the power supply suspect. Note that fans and HD motors use 12VDC. But other critical devices, such as the CPU and RAM use 5VDC and 3.3VDC, also from the PSU. All three voltages must be good in order for the computer to be happy. Below are my two canned texts on testing, then choosing a new PSU. You should test your RAM too, but you need a good supply first. Then sadly, it would be time to look at the motherboard.

I would also try your bad monitor on another machine.

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To properly test a power supply unit (PSU), a qualified technician puts the PSU under various realistic "loads" and analyzes the voltages for ripple and other anomalies using an oscilloscope or power analyzer.

I keep a FrozenCPU Ultimate PSU Tester in my tool bag when I am "in the field" and don't have a good spare power supply to swap in. While not a certain test, they are better than nothing. 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.

As mentioned, a good alternative test method is to swap in a known good supply (with ample power).

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 main power connector, deep in the heart of the computer. One tiny slip can destroy the motherboard, and everything plugged into it. It is not worth the risk considering the multimeter, like plug-in testers, do not measure, or reveal any unwanted AC component to the DC voltages.

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) - there's a good chance if you had a UPS in line, this would not be an issue today.

Thanks for the reply, i'm going to try the monitor and video card in a different machine, i'll also try removing ram and dvd drive.

I have a huge supply of PSU's, i'll go and have a look at them and see what they are, they orginally came from gaming PC's so i would susspect they are good?

Nick

Thanks again for the help.

I took the video card and 1 stick of RAM out of the PC and it has started up fine, so it looks like it was the ram.

Nick

Great! I am glad you got it going and thanks for the followup.