intermittent post failure

  rickd 17:03 10 Feb 2008

I posted this problem a couple of weeks back, and have had a chance to try most of the suggestions – thanks for those, but the problem is back.
Specs: an8-32 sli, 4800+, 8800gt, 550w psu, 2x1gb ram, xp. 18months old.
Some days (like today) when I power on my PC I get the power & HD lights and MB light, all the fans (case, psu,cpu, gfx) power up but it doesn’t post – no beep or video signal. I turn the power off and try again usually with the same result, though sometimes the dvd drive lights come on and the power light goes off. I try again maybe an hour later and it may, or may not post, but sooner or later (maybe next day), it posts as it always used to and then runs perfectly. It may then start perfectly for days at a time before the problem occurs again. Last time it played up I switched the RAM around, re-seated the video card and CMOS battery, checked all the connectors, unplugged all the USB’s, none of which helped. When I did get it started, (not apparently as a result of anything I’d just done) I checked everything was up to date and ran tests on the HD’s.
I initially suspected the psu, but why would it be so intermittent, and why doesn’t it fail when I really draw power (like when running the graphics full on). It’s under warranty, but my fear is that when I send it back, it’ll work fine for them and they’ll do nothing, so I’ll be no further forward, just wasted time. I could go and buy a new PSU to try, but would rather not as a) its money and b) if it is the psu, then it should be changed free under warranty. I don’t have a voltmeter or any electronics training to test it myself.
I just wish it would completely die so I could send it in, but it keeps just hanging on in there… for 2 months now!
Anything else I can try?

  Fruit Bat /\0/\ 17:41 10 Feb 2008

Classic symptoms of PSU on its way out.

Heaviest load is starting from cold.

  rickd 18:23 10 Feb 2008

Thanks Friut bat, that's where my suspicions lay at first, and I buy into the "heaviest load at start-up" idea to some extent, but surely the heaviest load will be when the graphics card draws another 200 watts playing games at full stretch (I didn't think the card fired up fully until after post anyhow), but don't get why it doesn't works one minute, then does the next.
And.. true to form, I just tried again and its fired up perfectly. I didn't touch a thing in the meantime. Is this really in keeping with a dying PSU?, and if so, isn't 2 months of sickness long enough for it to curl up its tootsies for good. Do you think I could convince MESH that this is the problem so they might send me a replacement PSU on the basis of these symptoms? I have doubts. Anything else at all to look at before I go just go out and buy another PSU?

  Fruit Bat /\0/\ 18:44 10 Feb 2008

depends what part is failing on when it cuts out.

12v rails heavy start to get HDDs moving on startup.

G card may only be drawing heavy on the 5v rail.

Heat also makes a difference as resistance changes with heat.

  skidzy 18:46 10 Feb 2008

I agree with Fruit Bat /\0/\ possible failing psu.

It looks like you tend to stress the machine with games and a decent graphics card.
Correct me if im wrong here,but Mesh tend to fit under powered psu's just like a few other retailers.Just because it says 550w,this does not mean you are getting full power from the psu.

I would advise you to consider a named/branded psu of 500w upwards.

Have you run Memtest to rule out any ram errors ?
Memtest (direct download) click here

Download and burn to disc using Nero or Imgburn click here
Check your bios is set to boot from cd/dvd
Insert the bootable Memtest disc and reboot the computer,let Memtest run for a couple of hours.

Also consider it could be a faulty mobo or graphics card !

  rickd 19:10 10 Feb 2008

Cheers Fruitbat, that sounds like a feasible explantion, but still don't see why it does it one minute, not the next, but I guess thats transformers for you.
Skidzy, the PSU is a HEC550TD-PTE. Is that any good? It wasn't a cheap PC by any means.
The gfx card was new a few weeks before the problem (so I initially wondered about it), but it works fine (once booted!), and for some reason I thought the card didn't fire up until after post.
If its the Mobo, I just wish it would go ahead and die now!
I'll try memtest tomorrow.

  woodchip 19:14 10 Feb 2008

Post beep only covers the 5volts rail on motherboard, Suspect Hardware problem connected to mobo or it can still be PSU. Can also be faulty joint on mobo

  rickd 19:16 10 Feb 2008

Hi Woodchip, can you expand on that a bit?

  woodchip 19:21 10 Feb 2008

The post beep is PSU sending a signal to motherboard 5volts if things check out OK then you get the beep to say it's ok. But a dry solder joint can create this stop go that you are getting, problem is finding such without using the swap out method

  rickd 18:14 06 Mar 2008

For anyone interested in the outcome....
A week after starting this thread the PC finally gave up posting altogether, so it went back to MESH, who diagnosed a failing Mobo, replaced it and couriered it back within a week. Apparently the PSU was fine.
Now runs like a dream again.

  woodchip 10:42 07 Mar 2008

as i though dry joint on motherboard

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