HTPC refuses to boot after current failure

[Jacobus Serpenti]

Hello everybody, after having sought on the forum, I did not find anything conclusive regarding the breakdown which has just arrived to me.

Following an interruption of current, my HTPC does not start any more (it was extinct when the cut took place): a pressure on the power button makes the fans turn during a split second, then nothing anymore, only the power led on the front panel blinks very slowly; any pressure on this button or the reset button does not change anything.

On the other hand when I disconnect the power lead to the CPU (an AMD athlon64 3500), noted JPW1 on a MSI K8N Neo4 platinum, the system starts (but as the CPU is not fed, nothing happen which is normal).

I proceeded by elimination: memory ok, graphics board ok, power supply ok since the preceding test confirms its operation.

Must I deduce from it that it is the CPU which is broken down or would be this nevertheless the mother board?

Hope to be hearing from you soon!!!

Best regards

jacobus serpenti

[Soopafresh]

It is most likely the motherboard. I've seen exactly the condition you describe.

[Jacobus Serpenti]

Thanks for your reply Soopafresh.

So it would be the motherboard? Not the CPU?
Well I guess I'm to buy a new one

Best regards
jacobus

[TBoneit]

Before I bought something expensive I would try a power supply first. Unless you disconnected the AC to the computer either through a switch on a power strip or a switch on the back of the power supply the power supply is always on. The power button on the front of the case is a low voltage switch that connects to the motherboard and through that to the ATX power connector to the power supply. That lead you decided only feeds the CPU feeds other parts too.

I have seen power supplys that lost the ability to provide enough power to run the computer that could still run their fan(s) when disconnected.

[Jacobus Serpenti]

Good evening TBoneit,

I don't quite understand your reply, since my hardware knowledge is limited, sorry!. At the back of the power supply (a TAGAN 380W) is a switch to turn it off. When I turn it on again, the fan of the power supply, of the 6600GT and of the CPU turn a split of a second, then every thing stops. And the front led blinks slowly.

So an unexpected power loss could have damaged the power supply, although according to the specs, it is supposed to be protected against power peak ?

[aedipuss]

turning the power switch off and on in the back of the pc should do nothing at all. no lights no fans nothing blinking. it's not until the power button on the front is pushed that anything should occur.

i would also start with replacing the power supply in a case like yours j.s. they are fairly cheap and easy to swap and unless you also have a very good surge protector it's connected to, easily damaged by a power spike.

[Bjs]

Most do have some protection , but its limited .

If the unit was connected directly to power point , you start with a NEW power supply , and in the 500watt range for that amd chip , and connect it to power point via a power board with some form of active spike protection .

Dont complain about those cheap $20.00 units , they do work , even if it is basic protection , better than nothing .

Msi mention the four pin connector supplys power for cpu , but the blinking light part is strange . So start with a new power supply , no matter what you do , or what led you to believe the memory , video card , ect , are fine , it cannot be ruled out as a common factor .

Strange crap happens when it comes to power supply faults , and it sounds as though the psu is not delivering power to the cpu at all .

Check the function of the power and reset buttons on the case , on some occasions , these do stuff up , which cause the system to either enter a restart loop , or to sit and wait .

After replacing the psu , disconnect all drives , and see what it dose from there . A drive that has developed some sort of failure can also cause a pc to sit in "holding" position , and go no further .

[Jacobus Serpenti]

Hello Bjs and Aedipuss,

Thanks for the advices, I'll go for a new PSU.

I would like to mention that I tested the memory on another PC, it was ok, so was the 6600GT also

Why a 500W PSU ? since I'm not a gamer, it's a HTPC and an mpeg2 encoding station, it doesn't need that much power, don't you agree ?

Be reading you

jacobus

[rallynavvie]

Should move this to Computer...

[Soopafresh]

Because the fans revolve for a fraction of a second, they're receiving power. Betcha it's the mobo.

[redwudz]

Should move this to Computer...

Done.

I would replace the power supply mainly as you said the problem was after a power failure. A new PS would be good insurance if it turns out you have to replace the motherboard. Power supplies aren't that easy to test and it may have failed if there was a surge. If you can substitute a PS, that would be cheaper. 400 - 500W seems a good range for the system you have.

I suspect you have a motherboard failure, though and hopefully not worse. If you replace the motherboard, you don't want to have new problems caused by the old power supply. But do try unplugging all drives except boot and all cards except the video card first and see if that does anything.

[Jacobus Serpenti]

Hello Redwudz

I did a test as you described : only the boot drive, the mobo and the cpu (the 6600GT being fed by the mobo) : nothing but the same symptoms as described earlier

I think I'll have to disassemble the HTPC and test the PSU on another PC, if it operates there, then probably it has to be the mobo which is broken, don't you think so ?

Be reading you soon

jacobus serpenti

[redwudz]

Yes, that should be one way to test the PS. Often the easiest way diagnose computer problems is to first eliminate as many probable causes as possible by disconnecting non-essential parts. Then substitute what parts you can to narrow it all down further.

From your descriptions, either the power supply or the motherboard would be the most likely as the cause. If it is the motherboard and not the PS, then hopefully everything else is OK.

[Jacobus Serpenti]

Hello again Redwudz,

I just have tested the PSU on another system, unfortunately not exactly the same as my HTPC. But the PSU works, although I had to make some changes : the plug to the mainboard has less pins so it had to disconnect a 2x2 square plug from that to the mainboard on my HTPC, also the 2x2 plug to feed the CPU on my HTPC is not used on that other system.

That other system also needs less power since it is only an athlon XP 2.2 GHz.

But nevertheless since on my HTPC the system "runs" when the CPU is not fed and stops when the CPU is fed, and since even if there was no power coming out off the plug to the CPU and the system would still "run", then I conclude out off this that either the area of the mobo around the CPU is broken either the CPU is dead

Is this weird or plausible ?

[rallynavvie]

Look at the motherboard in your HTPC, specifically looking for the tall cylindrical capacitors. They're usually located near the power connector or memory. Look at them carefully and look to see if there is any leakage or if the tops of them look bulged out at all.

I've had several computers at work suffer from bad caps (as well as one of my own right now) and they have some of the same symptoms you're encountering.

[Bjs]

I just have tested the PSU on another system, unfortunately not exactly the same as my HTPC. But the PSU works, although I had to make some changes : the plug to the mainboard has less pins so it had to disconnect a 2x2 square plug from that to the mainboard on my HTPC, also the 2x2 plug to feed the CPU on my HTPC is not used on that other system.

This still dose not rule out the psu not being at fault as that 2x2 is required by the msi motherboard to supply power to the cpu ... thats what it says in the manual for msi motherboards .

Some systems by design have no requirement for that extra plug , but some do , which cannot be overlooked , as it may have failed along this path only , yet still appear to be fully functional in every other department .

The only way to be guaranteed it is not a psu issue is to install it into another system that DOSE require the extra 2x2 plug .

A replacement psu is far easier and cheaper to replace than the motherboard in many cases .

Most modern motherboards are designed to halt operation if there's an issue with the psu .

Mine screams a load siren if vcore is not up to scratch ... frightened the crap out of my niece ... she thought she broke it until I said it was not her doing , just the stupid pc had developed a fault .

Before she could finish her ice cream , it was back up and running again with a new psu .

----

rallynavvie means , electrolytic capacitors (little metal cans around motherboard) .

Yes they can cause the similar symptoms to appear .

Look for cracked tops .
A black tar substance (anywhere on them)
Compare discolourization and appearance with similar caps near by .
Buldging .

Blown out bottoms are hard to pickup unless the board is removed for further visual checking , and some are just in hard to see places .

One of my mates had several blown , yet the system was able to start and run , yet would reboot at anytime , irregular occurance .

To replace them you need a desoldering tool ($14.00au) , a low wattage soldering iron , below 20watts ($16.00au , some come with solder ready to go) , and replacement caps of same rating , not similar rating ... there's cheap and nasty caps out there .

Just remember , they only get installed in one direction , or they wont work .

Its an easy enough job to do , with steady hands .

----

What I hate is when people say can you fix it , it has sparks coming out of it .

I say ... where from .

Silly buggers , it was the lights from the rear lan panel they had never noticed before ... you got to laugh .

[Jacobus Serpenti]

Hello everybody,

And the winner is Soopafresh : the mobo is dead! as he pointed out since the beginning of this thread.

Well that's it, and since my CPU, an athlon 64 socket 939, is obsolete, I'll take this as an opportunity to update to a dual core system, more ram and a more powerfull PSU

And many thanks to the community for support, help and advice.

Best regards to all of you

jacobus serpenti

[redwudz]

Well, that's good and bad. Too bad your MB is dead, but updating to a dual core like a AM2 should be a nice improvement.

[Nelson37]

How have you determined that the Mobo is dead? I ask this because your original testing from which you determined the Video Card and Memory are OK is totally inaccurate.

Also, stop right now and get yourself an APC surge protector and/or battery backup. A less than $50 expenditure would most likely have prevented the damage, and paid you for your hardware expenses if the damage did indeed occur.

[Soopafresh]

And the winner is Soopafresh : the mobo is dead! as he pointed out since the beginning of this thread.


It's a hollow "victory". Bummer it turned out being that

[Jacobus Serpenti]

Hello Nelson37,

I went to a friend, where I tested the memory and the 6600GT; both they functionned. So the CPU, the MOBO and the PSU remaind, since the PSU seemed to operate, it could be either the mobo or the cpu.

Sorry for the confusion

jacobus serpenti

[Nelson37]

That explains it.

The only thing I would stress is that your statement "The PSU seemed to operate" is not correct. It still could have been the source of the problem. There are several different outputs on the PSU, with several different voltages. Often some are affected and some are not. In fact, mobo power seems to be much more likely to be affected.

It is far more common for the PSU to blow, a defective PSU often operates as you have described, and it is cheaper and easier to replace. In my area, I keep not just one but two in stock at all times.

Considering the low price of a PSU, along with your investment in new parts, I would highly recommend replacing the PSU as well. Flaky or inconsistent power can damage your new parts. A PSU which has had a significant surge run thru it may very well be damaged, often the damage is not obvious, or may manifest itself in the near future.

I live in the lightning strike capital of the world. Cases like yours are quite common. In such cases, I replace the PSU. EVERY TIME. Most Especially after spending cash on a new CPU and motherboard. If the customer asks me to replace the board and not the PSU, I will refuse to do the job. It is that important. Think about it, whatever damaged your mobo came through the PSU first.

I also get the customer an APC battery back-up. If you had had one, you would still be happily working away, minus the frustration and effort you have had to expend.

It's like fire insurance. Most folks are not real concerned. BUT - Once you have come home to the smoking embers of what used to be your home, the only further question you will have about fire insurance is "where do I sign?"

[Jacobus Serpenti]

Thank you Nelson37 for these words of wisdom.

Best regards

jacobus serpenti