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Billy T
05-06-2013, 12:57 PM
I didn't want to reprise this problem (http://pressf1.pcworld.co.nz/newreply.php?do=postreply&t=131155) :( but guess what happened when I fired up my computer last night after we got back from our trip? :waughh:


I had not turned it off since the last episode as I needed to catch up on my work, but I have "restarted windows" several times since then in response to update requests etc without any problems. Acting on previous advice, I pulled all leads other than keyboard, monitor, and mouse and it still wouldn't post. Power to the computer is stable so we won't go there.

After several attempts it did restart (much to my relief, as Mrs T was in my ear something terrible :angry because I'd turned it off before leaving) and it is once again working normally (so is Mrs T, thank heavens).

On checking the back-history of threads on this issue, I see that some parallel situations were diagnosed as motherboard faults. So, I'm prepared to change the motherboard (ASUS P7P55D EVO) if required, but apparently that will also require a CPU change. The next big question is, will my OS and programs disk be affected by a MB change or will it carry on as normal once the board is set up?

It hasn't been my week for "failures to start" but that tale will come up in Chat later on.

Cheers

Billy 8-{) :confused:

P.S. Did I see somewhere that ASUS MBs had a three year warranty, or am I dreaming?

zqwerty
05-06-2013, 01:56 PM
It's the PSU, this is exactly the fault I have described many times on PressF1, the self starting bi-stable multivibrator is dependent on two electrolytic caps which are positioned in a hot area of the PSU pcb, as time goes on they deteriorate and first signs are will not start in cold ambient temperatures (sitting around in a cold room for a couple of days) then after a number of tries they warm up and will start the PSU.

The next time this happens, warm up the room for a couple of hours and then try again, bet it starts first time.

Billy T
05-06-2013, 09:20 PM
That makes sense, but can I check one thing with you?

At switch-on the blue 'power' led comes on, then the red led for disk activity
comes on briefly then goes out again, but the blue power led stays on regardless.

I would have thought that the blue power led would not light or go out if the supply
failed tokick off, but then I'm not familiar with the architecture of computer supplies.

Clarification on this point would be helpful.

Cheers

Billy 8-{)

(What I really need is a Southern Man with jumper leads!)

zqwerty
05-06-2013, 09:44 PM
Ahhhh ok, sorry, no the fault I am refering to is no activity at all (no lights) but there are no blown fuses and the PSU on inspection seems to be intact and in working order but just won't start. Sometimes the cooling fan will give a small 'kick' but nothing else happens.

So can you measure the 12v and 5v rails etc? See if they are present even though the computer does not start.

Wonder if the HDD won't spin up when it is cold? See if it spins up at all by feeling for vibration at start up, HDD's exhibit this phenomena when they are cold and getting old.

I think the key to finding this fault is to realize it's probably temperature related and find out what needs to warm before it will start.

I have sometimes found temperature related faults with a can of "Freeze" in one hand and a hairdryer in the other, using a nozzle on the dryer you can narrow the offending component down, however this was on video games boards back in the 80's, complex motherboards but not much like todays computer motherboards.

Intermittent problems are always tricky to find.

Definitely think you should try another "known good" PSU to eliminate that possibility.

Speedy Gonzales
06-06-2013, 11:48 AM
Is BIOS 2101 on it?? And are you still running in RAID?? Looks like this updates fixes

Fix RAID HDD size issue.

*Note: Update Intel(R) Rapid Storage Technology Driver to v10.5.0.1026 to support full HDD capacity. (The downloaded file has contained the driver.)

Billy T
06-06-2013, 07:15 PM
The BIOS and IRST driver(s?) were updated by Computer Lounge about 4-5 weeks back after the last 'failure to start' and I hadn't turned it off since then until we went away last week. I could see that the Intel drivers had been changed last time I took it in because there was a new icon style in the System Tray and a different desktop icon for some other related function that I don't recall just at the moment. I was bl**dy surprised when it finally restarted at all this time as it has resolutely refused on all previous occasions, no matter how many times I tried.

Just to recap the symptom, the blue power light comes on and stays on, the hard drive light starts up briefly then goes out and that is it! It does not get to the RAID or Motherboard splash screens and the monitor stays blank throughout.

I probably tried 12 or more times over a 15 minute period because I stopped after the first few and got under my desk to pull the USB connectors out and anything else too except the power plug, the keyboard and the mouse. The latter two run through a manual KVM switch. I even tried turning off the PSU itself to give it a 'cold start'.

I have monitored the output volts, waveform and noise levels on my UPS and they are perfect (230volts RMS, clean sinewave, common mode and normal mode noise <250mV), but I wasn't expecting any surprises there as it is a full-time on-line 1000VA Dynamix sinewave output jobbie, badged as DIGITECH for JAYCAR and shows no sign of any fault.

Cheers

Billy 8-{)

zqwerty
06-06-2013, 08:50 PM
When I am typing PSU I am meaning the box inside the computer not the uninterruptible power source.

dugimodo
07-06-2013, 10:18 AM
The symptoms you describe do sound most like a PSU issue but there is no way to be certain. All kinds of hardware issues can prevent booting, even down to disconnecting all internal drives to see if the machine goes to the BIOS reliably without them connected then connecting them back 1 by 1 to see if any are causing the issue - same with anything else connected that can be done without temorarily. Another thing that can cause it is a fan that is not starting reliably, either the CPU or a case fan connected directly to the motherboard which is not spinning fast enough to satisfy the BIOS that it's working causing it to shut itself down.

Also did you ever try without the UPS? I know you are certain it's not the problem but how hard is it to plug it into a wall outlet and prove it so we stop asking you ?
Repeating myself from the original thread, think what's different between the two enviroments and try to eliminate things 1 by 1. If it's not connected when they test it in the shop, don't connect it at home and see if that works.

Sometimes the act of moving the PC makes things work, usually when something is not seated quite right or a connection is not 100% somewhere, go over all the connecters inside and out and confirm they are all making good contact, check the RAM and graphics card are seated properly and try taking them out and plugging back in a few times (cleans the contacts a little), try a different power cord (reaching but why not?), etc

Good luck, these kind of problems are extremely frustrating to track down at times.

Billy T
07-06-2013, 11:11 PM
When I am typing PSU I am meaning the box inside the computer not the uninterruptible power source.

That is a given, my reference to the UPS was for the sake of Dugimodo who kept insisting that it could be the UPS.

I posted to cut that one off at the pass. Power is my profession and I'd be the first to know if the UPS was not delivering the goods, but I ran a full battery of tests just for the halibut (in case there was something fishy going on!) :D

Seems we have a choice of PSU or Motherboard as the guilty party

Cheers

Billy 8-{)

dugimodo
08-06-2013, 09:45 AM
That is a given, my reference to the UPS was for the sake of Dugimodo who kept insisting that it could be the UPS.

Wasn't just me :(
Anyway you are probably right and it probably isn't, the insistence is more about actually trying without it to prove it. All the tests in the world are not the same as eliminating from the picture altogether.

I'd be focusing on the PSU or motherboard as you suggest except the fact that the problem went away at the shop, that throws a spanner in the works and leads to the question, what's different?

Anyway nothing more useful to add, good luck.