Need some advice on diagnosing a power problem

[ChromaticRanger]

Hi

I built myself a new system about 8 months ago. This was my first ever attempt and although a few things were a bit tricky all seemed to go well and I have been very happy with the machine, however over the last few weeks I've been having power issues. I imagine it must be the power supply but I'm not sure how to go about isolating things other than my very layman approach so far.

So, what has been happening is that most of the time now when I press the power on button nothing happens. If I then go to the main 'rocker' switch at the back of the case and flick it on and off, if I am lucky the system will fire up after a few attempts. Sometimes I can be trying for a few minutes of flicking on and off before it sparks into life. Until a few days ago once it is on everything is fine. O/S is stable. Runs like a dream. However, a couple of days ago and again tonight, the power cut out as if the mains had been switched off. I took the power out and left it for a while then tried my normal procedure of switching from the rocker, but this time after about 10 minutes, no go.

What IS happening though as I am switching on and off from the rocker, is that occasionally as it goes to the on position, everything sparks to life for an instant but then goes off again straight away.

Another thing to mention is that ever since I put the machine together the power supply fan has never spun up. I did read up on this when I first put it together and read a few posts (not sure where now) that this was actually normal as the machine was not under stress. So I discounted it as an issue.

I figure I've got a loose connection, but maybe inside the power supply, rather than the power supply being dead, as it does fire up after a while, normally, but wondered if anyone else has had a similar problem and can share what things I should try.

Many thanks,
Martin

Spec

- Corsair Graphite Series 600T Mid-Tower Gaming Case
- ASUS 1155 P8Z68-V PRO S/L
- Corsair CMPSU-850AXUK Professional Series Gold 850W Power Supply
- LG BH10LS30.AUAR10B 10x Internal Blu-Ray BDRW Retail Kit
- Corsair CSSD-F120GB3-BK Force Series 3 120GB Solid State Drive
- Western Digital 2TB SATA 6Gbps Power Saving Internal Hard Drive OEM - Caviar Green
- Corsair CMZ16GX3M4A1600C9B 16GB (4x4GB) 1600MHz CL9 DDR3 Vengeance Blu Memory Four Module Kit
- Intel Sandybridge i7-2600 Core i7 Quad-Core Processor (3.40GHz, 8MB Cache, Socket 1155)
- Thermalright Venomous X RT - Processor cooler
- Sapphire 11180-00-20R HD6850 1GB GDDR5 Graphics Card
- 1 x BenQ BL2400PT 24-inch W LED 1080p Monitor
- 2 x Viewsonic VX2260WM 22" widescreen 2ms LCD TFT Monitor
- OS Win 7 Ultimate x64

 

[ChromaticRanger]

Hi

Thought I would come and add an update to my own message. Thought I would have had some suggestions by now.

This morning my PC did not start as usual and it took about 30 mins of 'fiddling' with the power supply connections and switching on and off from the rocker switch until it powered on. This is by far the longest it has ever taken to respond.

As usual once it was up and running all seems fine and stable. I played on-line Diablo 3 with a friend but after about an hour the dreaded power down happened. Instant loss of power as if we had had a power cut or the mains had been switched off.

I think I'm resigned to paying for a maintenance guy to take a look at it, but thought I'd ask one more thing.

When I do switch the power to the ON position at the rear of the PC, various lights on the motherboard DO come on. So obviously some power is getting through the power supply, just something is stopping it from 'firing' into life.

I'll post more if anything else comes to light.

 

[manofchalk]

So you lost power, and since then the PSU has only intermittently worked. Sounds like it took a power surge and that has either tripped an internal circuit breaker or just legit ruined it. Do you have any measures against power surges (like a surge protector at the wall or power extension board)?

The simplest way to tell if the PSU has been busted is to replace it with a known working supply. So if you have an old rig somewhere, grab the PSU from that and see if it will boot/work from that supply. If it works without issue, then the current PSU is at fault.

If not, it may be other causes. From here I advise to just go through general troubleshooting.
http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

These steps will eliminate most possible issues, if it still doesn't work, it is likely that a component other than the PSU has failed.

 

[ChromaticRanger]

Hi

Many thanks for the reply. I shall take a look at the general troubleshooting link and go through the recommendations.

I am using a Belkin extension board that says it has surge protection, but I take your point that maybe a surge has occurred. I also take your point that it could also be another component further into the power process. Unfortunately I do not have another PSU to swap in.

Its frustrating that, in isolation, I cannot tell whether the PSU is working or not. I've taken it out and plugged it into the mains without connecting it to the PC at all and when I switch it on at the rocker switch nothing happens at all. It has no lights of its own, the fan does not move at all. The fan not moving has always seemed odd to me. I cannot be certain but I am fairly sure it has never spun.

I'm itching to take a screwdriver to the PSU as it feels like its the switch that is the problem (seeing as when it does start, all is fine??). Its only 9 months old though so I figure I should still be under warranty.

Once again, many thanks for the reply, I'll let you know how I progress.

Cheers,
Martin

 

[manofchalk]

I advise against opening up the PSU and tinkering with whats inside. Many of the capacitors in there can hold a lethal charge for quite a while, so accidentally shorting one can kill the supply or yourself.

You can test if the Supply works on a basic level. Remove it from the rig (seems you'v done so already) and connect a case fan to it, or something that will light up or obviously work. plug the supply to the wall, and grab the 24pin ATX cable. Inspect the plug for a green wire, short that out to any of the black wires and hopefully the fan will spin. So that'l tell you if the PSU works on a basic level.

Heres a tutorial with some pic's.
http://www.overclock.net/t/96712/how-to-jump-start-a-power-supply-psu-test-a-power-supply-and-components

 

[ChromaticRanger]

Hi

I like the idea of that test, although a little nervous about the bit were you stick the paper clip in whilst it is ON.

I do however have a fundamental problem with the method. The Corsair 850AX PSU that I have came with very uniform black chunky cables, so my 24pin ATX cable only has black wires going into it! In fact every cable that you plug into the PSU has only black wires into the connectors at either end.

 

[manofchalk]

Look in the manual of the PSU, somewhere in there it should show you what each pin on the 24pin ATX cable does. On the user manuel for my PSU, two pins are labeled "PS-ON". Shorting those two out has started it before.

Its perfectly safe, those two pin only have a very small charge (not enough to pass through skin) as they dont actually supply power, just sends a signal to the PSU to start working. If your hesitant, use an insulated bit of wire.

 

[ChromaticRanger]

Hi. Just wanted to update on the situation.

I took my machine to a local engineer who after some testing decided that the probable cause was a fault with the motherboard. He put my power supply in another unit and it worked fine apparently. After a lengthy attempt to do an return to Asus they eventually told me that I needed to send the MB back to Amazon. Amazon did not have an exact replacement in stock but refunded me without question and I bought a new MB. Same make new revision.

Anyway, to cut a long story short I've had the machine re-built with the new MB .... and after a few hours of working fine it has started to display the same problem again!

I've just mailed Amazon to see if I can get a replacement for the power supply. Very frustrating.

Martin