No bootup

[uid0]

hi guys,

Need some help.
There were "random" occasions of the same problem for the past few months.

when power on, power light on but no bootup.
all fans running including graphics card.
no post and no beeps.
not able to reset and power off (4 secs)

1. cleared CMOS
2. cleaned contacts on graphics card and RAM
3. inserted RAM each separately
4. checked all connections

hardware:
Asus P5B E Plus MB
2x1 Kingston RAM
2x1 Twinmos RAM
EVGA 7950GTO
Seasonic 650W M12

System had been running for about 2 years.
Any Suggestions?

[P.Pilcher]

Almost certainly power supply failure: one of the many voltages that the motherboard requires from the PSU is missing. It has happened to me several times. Cure: Obtain and install new power supply. It isn't difficult.

P.P.

[uid0]

Thanks PP.

Did a self test on the psu as recommended by the manufacturer. it seems the psu is working fine. installed another gfx card and the problem persists.

Since the MB is still under warranty (Asus-3 years warranty), will send it to vendor and check.

[Saab Dastard]

Could be a CPU failure. Check that the CPU is seated fully, and the heatsink is making good contact. Check for any bent pins while you are there.

Probably best to remove the heatsink, clean the contact surfaces and re-assemble with some thermal paste.

SD

[Jofm5]

You should still get the post beeps even if the cpu or the memory has failed.

It does sound like power - not sure what self tests you can do on the power supply other than by checking the fan on the PSU is working and by attaching a device that will always run to one of the cables (e.g. a fan).

Other than power - no beeps etc does look towards the Motherboard

[BOAC]

I'm not familiar with your machine, but do you have hard drives and do they run? Some mobos also have led hex indicators for boot stages tucked away somewhere..

[al446]

Yep, sounds like PSU to me. How can you check it if the whole thing aint booting or getting to POST?

[Jofm5]

Yep, sounds like PSU to me. How can you check it if the whole thing aint booting or getting to POST?


POST = Power On Self Test which is performed by the motherboard, this is the stage prior to the motherboard attempting to load the bios and boot. If at any point during this process the test fails the motherboard will emit a series of beeps indicating which stage of the POST it failed on.

Therefore if you are not getting any beeps it is either the motherboard or the powersupply. If you can prove the powersupply which can only really be done correctly with a volt meter - then it your next suspects would be the motherboard or the connections to the motherboard (assuming your cables are checked and proven).

[Keef]

But PSU is the way to bet.

I've replaced about half a dozen failed power supplies for friends in the last 12 months, and not met a single motherboard failure.

I keep a couple of spares in the cupboard, ready!

If you're replacing it, get the highest-rated one you can fit in the case. I buy 500 watt ones now - not a lot dearer than 300 watts, and a lot less likely to fail through overload.

[Jofm5]

I agree Keef,

But I dont know what this self test is that has been performed on the power supply - I have not heard of this before (but thats not saying its wrong).

For £20 for a decent replacement powersupply delivered next day I personally would try that first, however I may be lacking information and if the powersupply does indeed prove true - I would suspect the cables before the motherboard - but the motherboard is the next logical choice.

I only say that because I have never seen such a catastrophic failure of a mother board in my 20 years of commercial progarmming - but that dont mean it does not happen :}

Would be good to know what you isolate it to in the end.

[Jofm5]

BOAC:

I'm not familiar with your machine, but do you have hard drives and do they run? Some mobos also have led hex indicators for boot stages tucked away somewhere


If your motherboard will not post none of the drives will spin up.

The reason for this is power comsumption, the motherboard will start each drive one after the other - hence a single drive machine will boot faster than a multiple drive machine.

The reason for this is the power consumption required to take the drive from a stand still to spinning - if all possible drives were powered on at the same time the draw on the power supply would be too much compared to the fraction of the power required to maintian the speed. Therefore all motherboards will start the drives up sequentially, so no huge draw takes place.

[P.Pilcher]

Like others, I have never heard of a fully comprehensive power suply check that can be run - unless the computer is fully booted up and working. IMHO the only way to be certain is to check the voltage output at each pin of each plug when the power supply is connected to its motherboard. My post above was based on the following experience:
6 years ago, I acquired my first XP machine - a Maxdata with a service contract. After 18 months, no beeps and no startup. Summoned engineer who fitted new power supply. Normal service resumed. Two years later, no beeps and no startup - well, if you tried to switch it of and then on several times, eventually you might get a beep and startup would commence. Then it was necessary to remember NOT to switch the machine off!
Cure - fit another power supply.
Six months ago - no beep, no startup, acquired a further supply from P.C. World and problem cured - mental note to replace computer.
The other month while new dual core machine was being assembled, - No beeps, No startup. P.C. World replaced the power supply on warranty. Once again, Normal service resumed, however, new M/C now uses a power supply from a different source.

P.P.

[al446]

My posting (#7) was meant to be rhetorical, I was indicating that if he is not getting anywhere POST then the first suspect is PSU. After that mobo.

Hope that makes more sense. I would have used smilies but don't usually bother.

P.S. £20 = decent? :=

[Jofm5]

P.S. £20 = decent? :=


Not sure why you are waving the finger - a power supply that costs £20, is rated to do the job and turns a defunct PC from an ornament to a working system is fairly decent in my book.

Yes if you want seperate rails for different components for stability for example when using high end graphics cards you have to spend alot more.

But if you look at the power supply that comes as standard with just about all mass produced pc's you will see it matches the specification of the £20 dabs value replacement power supply I was reffering to.

It all depends whether you are comparing decent enough to do the job with excellent for the job.

[al446]

Perhaps one of the reasons for the finger wagging is that I notice the PSU uid0 has presently is a Seasonic, hardly bottom of range and THAT has blown (apparently). I would suggest that dropping the sights may give you instant boot but is probably a bum buy in the end. I am not suggesting the purchase of the cannine cojones but to go out and buy an inferior replacement would probably not be the best long term solution. There are PSUs out there for as little as around a tenner. there is also dirt cheap lubrication oil on the market but I would not let it anywhere near my car.

I have had 2 major PC failures in the past, both on same PC. Took it (cheapo) back to vendor who replaced PSU, the mobo it took with it and graphics card. 6 months later, same again. All down to cheapo PSUs.

Your background may be in software, mine is in avionics/electronics, started almost 40 yrs ago. I leave it up to others to decide which path they wish to take.

Never confuse cheap and inexpensive which I am not doing in this case. Happy coding.

[The late XV105]

This thread is of interest to me too as from new (Dec 2006) mu ASUS P5N32-SLI based PC has behaved what appears to be similarly

Normal boot

1: Power on
2: Wheeeeeeeee (all three fans start)
3: Several seconds pass
4: "Beep" from mobo speaker
5: Wheeeeoooooooooh (all three fans drop in pitch and volume as boot sequence proceeds and the three SATA and one eSATA HDDs start up one by one)

Occasionally though boot never gets parts step 2.

As a case in point, last night I got home to find the PC still at the "wheeeeeeeeeeeeeee" stage from a failed boot that the missus initiated two days previously (without realising she could safely press and hold the power button or simply switch off the mains supply to force power down)

[Saab Dastard]

Occasionally though boot never gets parts step 2.

What - if any - message is on the screen when left in the "limbo" state?

I have noticed that it is not uncommon for hard disks not to spin up fast enough to report present when the boot sequence looks for the boot disk, in which case a "non-system disk or disk error" message usually appears.

This usually happens when more than one disk is present on an IDE channel. As I've not used SATA much I haven't experienced that problem with it - yet.

It could be a power problem, in which case I'd expect SATA to behave similarly to PATA.

SD

[The late XV105]

A plain black screen, SD.
No message.
Just whizzing fans, a stable power LED and no HDD activity LED.

By pure coincidence though (I was actually searching for something else) I found the following thread a few minutes ago that points to something similar.

ASUSTeK Computer Inc.-Forum- P5N32-SLI Premium Motherboard won't POST or error BEEP (http://vip.asus.com/forum/view.aspx?board_id=1&model=P5N32-SLI+Premium&id=20080829030204968&page=1&SLanguage=en-us)

[green granite]

I think my computer can read, it did that this morning. :suspect:

[Albert Square]

I had a problem with PC failing to boot. All fans running so PSU seemed OK and I checked all the voltages anyway with a meter. I had a POST indicator attached to the MB which indicated failure of the CPU so changed that but still no boot.

I finally discovered that there was no voltage at the power OK pin on the ATX supply connector. When you start the PC, the PSU powers up but, in case it takes a second or so for the supply to stabilise, it does not allow the CPU to operate. This is so the CPU only has a fully stable supply. When the PSU decides it is OK, it supplies 5v on the power OK pin (no 8) and the CPU starts. Without the 5v you wait forever.

My PSU did not deliver this 5v even though all voltages on all other pins were OK. Whether a fault of the power on system or maybe the voltages were unstable, I don't know.

I was a bit annoyed because i paid a lot of money for a high end PSU. A new (and cheaper) PSU solved the problem.

On a cheaper PSU, sometimes the power on 5v is just hard wired ie no checking of the PSU anyway so you would not get this probem (but more chance of a fried board).

Hope this helps someone.

[Avitor]

I keep reading of 'wizzing fans' *This may seem trivial but it isn't*. Look at the fans, make sure they are spotlessly clean, I had to find a sharp object to scrape around and inside my fan, it is difficult to get by the blades but it must be done, they do not wizz for nothing. All the snags went away after I cleaned them.....and added some memory strips! I never hear a fan now.

[The late XV105]

I keep reading of 'wizzing fans' *This may seem trivial but it isn't*. Look at the fans, make sure they are spotlessly clean

I can't speak for others but mine are spotless; every few months the fans get a clean and the inlet and exhaust grilles cleared of fluff, the last time being a week ago. The "wheeee" I referred to in my post is the high speed running of the fans before boot commences. When it does, the fans appear to slow down and become a near silent "whoooo".

[Parapunter]

[QUOTE]The "wheeee" I referred to in my post is the high speed running of the fans before boot commences. When it does, the fans appear to slow down and become a near silent "whoooo".


Well, the good news is your BIOS is working just fine.