Computer not turning on after replacing PSU

July 12, 2011 at 12:22:56
Specs: Windows 7 32Bit, Intel Dual core 3.2 GHz, 4GB RAM

Hi all,

My computer recently turned itself off without any warning and would not turn on again. No power was getting through to any of the components. I tried changing the fuse, changing the plug, nothing.

Assuming it was the PSU I bought a new one of the same power.

Old one was an Enermax Pro 82+ 600W, the new one is a OCZ Stealth X Stream 600W.

After attaching all the cables to their required components, the 24 socket on the mb, the PCI-E 1 and 2 into the graphcis card and the SATA cables to the hard drives and then the case fans and the optical drive to the Molex connectors, it turned on.

Only with no display on my monitor. I checked with a friend to see if I had all my cables plugged in and he said that the CPU 1 cable should be plugged in to the 4 pin socket on the mb.

So I turned it all off again and plugged it in, but when I went to turn it on I got a flash of an LED on one of my fans, it moved ever so slightly, and then nothing.

I checked without the cpu plug in and it would turn on, case fans running and everything but no display. Yet if I were to plug in any of the CPU cables from the PSU into the socket on the mb it would give me a very very brief flash of a single led, a twitch of a fan and then nothing. No sound from the psu fan, nothing.

My system specs are;

ATI 4870 HD 1GB graphcis card.
Intel Dual Core 3.2 GHz processor
MSI K942 CF Mother Board
4GB of RAM
OCZ Stealth X Stream 600W PSU.
NZXT Blackline Case

Any help would be appreciated.

~ Sam


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#1
July 12, 2011 at 13:25:45

The 4-pin ATX12V plug supplies power to the processor (aka CPU) & motherboard. The system won't boot without it.

http://www.playtool.com/pages/psuco...


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#2
July 12, 2011 at 14:09:34

"After attaching all the cables to their required components, the 24 socket on the mb, the PCI-E 1 and 2 into the graphcis card and the SATA cables to the hard drives and then the case fans and the optical drive to the Molex connectors, it turned on."

As mickiq has said, you must also plug in " The 4-pin ATX12V plug..." into the socket for that on the mboard.
.....

ATI Radeon™ HD 4870 Series System Requirements
http://www.amd.com/us/products/desk...

- 500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode)
- Certified power supplies are recommended. Refer to http://support.amd.com/us/certified... for a list of Certified products

Both your PSs have more than the recommended minimum capacity, however...

If you're a gamer...
In most if not all cases, the max capacity rating of the PS is an intermittent rating. It's recommended that you do not load your PS to any more that 80% of that rating if you are going to be using something that puts a constant load on it, such as playing a recent game for hours on end. In that case, you multiply the min capacity stated for the system with the particular video chipset on the card by 1.25 to find the min. capacity of the PS you should get.

In this case 500 x 1.25 = 625 watts
600 watts should be close enough to that.
......

If that doesn't help.....

Enermax PSs are high quality PSs .

I have installed at least a half dozen Enermax PSs over about 9 years and NONE of them have failed. In all cases, they had more than the minimum capacity recommended for the system for the video chipset on the graphics card in a slot it was using, if that applied.

However, it's possible for any PS to fail.

When a PS fails, it's possible for it to damage the mboard such that the mboard will not boot properly when you install a replacement PS. The lower quality the original PS was, the more likely that is to happen.
That's extremely unlikely to happen because of an Enermax PS failing.

NOTE that Enermax PSs have several features (anti-short, anti-overvoltage, anti-power surge etc.) that will automatically shut off the PS to prevent damaging it or the mboard or anything connected to it if it detects a problem that could cause damage. If something trips that feature, after whatever caused the problem is no longer there, the PS will probably NOT start up until AFTER it has been disconnected from AC power for a short time - e.g. 15 minutes or more - then it will start up fine.
.....

MSI mboards are well known to be more likely to have this problem.....

Some mboards develop this problem - electrolytic capacitors were installed on them that were not properly made, and they fail eventually - the mboard manufacturer didn't know they were improperly made at the time the mboard was made.

Open up your case and examine the mboard to see if you have bad capacitors, and/or other findable signs of mboard damage .

What to look for, mboard symptoms, example pictures:
http://www.badcaps.net/pages.php?vid=5
Home page that site
- what the problem is caused by
- he says there are STILL bad capacitors on more recent mboards.
http://www.badcaps.net/

Pictures of blown capacitors, other components, power supplies, fried Athlon cpus, etc.:
http://www.halfdone.com/Personal/Jo...
......

A static electricity discharge can damage the PS or the mboard or anything connected to the mboard.
Has your system been exposed to that since it last worked properly ?
E.g.
- using a regular vacuum cleaner to clean inside the computer case can do that - they produce a tremendous amount of static electricity when running, and can discharge that if you touch anything connected to the vacuum cleaner to anything inside the case.
- if you have synthetic wall to wall carpet where the computer is located and it the humidity in the room is low, your body can build up enough static electricity to damage something when it discharges when you touch something inside the computer case.

Power failure events can damage the PS or the mboard or anything connected to the mboard.

Has there been a power failure event, or a power spike or surge, or has there been lightning strikes in your area since the system last worked properly ?
.......

Sometimes a poor ram connection can cause your system to not boot normally.

A common thing that can happen with ram, even ram that worked fine previously, is the ram has, or has developed, a poor connection in it's slot(s).
This usually happens a long time after the ram was installed, but it can happen with new ram, or after moving the computer case from one place to another, and I've had even new modules that needed to have their contacts cleaned.

See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
http://www.computing.net/hardware/w...
........

You could try the Enermax PS and OCZ PS with another working system to rule out a mboard problem.


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#3
July 12, 2011 at 15:53:19

Thanks for the info everyone. Yes I plugged in the 4pin ATX 12V connector to the CPU and this is what was causing the fan to twitch and the light to flash for that split second as I described in my previous post.

I did try checking the power to the other components and this was happening, and I also got my friend whom I trust with all things computers to see if he could figure out what was wrong. We did check static and no there hasn't been any power failures, surges or lightning strikes in ym area. I make sure not to use vacuums on the computer and brush away any dust with a very soft brush. Though the concern over static build up is duly noted and I'll make sure that this can be definitely ruled out in any future cases.

My friend and older brother have thought it might have something to do with something on the mobo frying so I'm taking the psu back to the store and exchanging it for (hopefully) a Gigabyte one.

Also just to note I got my processor wrong in my original post, its a AMD 2 dual core 3.2GHz.

Thank you very much for your advice and help.

~ Sam


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#4
July 12, 2011 at 19:10:57

You could try the Enermax PS and OCZ PS with another working system to rule out a mboard problem.

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