randomly wont boot, no bios, then fine!

  rickd 12:44 13 Jan 2008

Several times recently I have powered up my PC from cold and it has failed to post, i.e. no BIOS. The fans all come on (PSU, CPU, graphics & case) and the HD light comes on, and I get a single beep. Then nothing more. After a while the HD light goes off, sometimes the CD drive lights come on, and stay on. I then turn the power off fully and leave it 10 secs or a minute and try again. After several attempts I usually give up, and when I try again maybe 10 mins or an hour later, it may, or may not fire up. When it has booted(as it just has), everything seems absolutely fine.
Its a MESH built, fairly high spec 2 yr old with XPSP2, 2Gb ram, 550W PSU, 8800gt, 4800+cpu. Clearly something is wrong/on its way out, but what to check first to stop this seemingly random, intermittent and highly irritating problem? I'm sure one day it'll stop completely, but until it does I can't really send it back to MESH, as sods law dictates it will work perfectly for them.
Everything seems to be properly connected/seated, and the PSU happily runs the graphics at full load etc when the PC is running, so I don't think its that. Could the BIOS be corrupted - but then why would it work sometimes and not others? Could it be RAM related?
The problem has only started in the last couple of weeks. A new HD, and new graphics card were installed couple of weeks before the problem started (with no immediate problems), so that may, or may not have something to do with it.

  rossgolf 12:51 13 Jan 2008

do you no what bios you have got ie. award or ami etc....

  rickd 12:59 13 Jan 2008

american megatrends. The MB was replaced by MESH about 6 months back, so I guess the bios is up to date

  Fruit Bat /\0/\ 13:24 13 Jan 2008

PSU happily runs the graphics at full load etc when the PC is running, so I don't think its that

Bad booting from cold is a classic PSU failing symptom.

Funny it seems to POST then freeze that sounds more like can't find opsystem on HDD but you usually get an error message.

The weakest point in DEL and Mesh PCs appears to be the PSU, have renewed many.

  rickd 13:45 13 Jan 2008

mmm, I suspected the PSU at first, but as I say, I don't have any probs once it actually starts (e.g. I can run the graphics at full speed on Crysis and it doesn't falter), so I'm not short on watts. Is there any way of checking the PSU output (short of buying a new one and seeing if that makes a difference or investing in a meter/degree in electronics). MESH would replace it free if I could proove it was bad.
I wondered if it could be the graphics card or some other hardware not starting from cold for some reason???, and this preventing the BIOS routine from completing??
No error messages in the Windows event viewer, but thats not surprising as it doesn't get to the point of loading windows. Is there a way to see BIOS error messages?

  DieSse 15:23 13 Jan 2008

"Several times recently I have powered up my PC from cold and it has failed to post, i.e. no BIOS. The fans all come on (PSU, CPU, graphics & case) and the HD light comes on, and I get a single beep."

A single beep is the normal sign of a successful POST. If you get that and the screen has not come on, then I would suspect the graphics card, monitor or monitor cable.

The best way to troubleshoot them is by substitution.

Before you substitute the graphics card, however - take it fully out of the case, clean the edge connector lightly with as eraser, refit firmly, and try again.

Don't forget to remove the power cable before doing anything inside the case.

  DieSse 15:25 13 Jan 2008

A few motherboards have a row of LEDs which show the boot status - look in your motherboard manual to see if you have, and how they display that status.

  rickd 17:13 13 Jan 2008

Thanks DieSse
So if it gets as far as the beep, this means the BIOS has worked right? well thats good news. But it still then seems to be waiting for something to happen before it puts the usual BIOS blurb on screen or continues to boot, and you think this could be the graphics card failing to fire up (although the fan is going)?
Some googling suggested that a cold card draws a lot to fire up, and this might be too much for the PSU. Does this seem likely given that the PSU runs the card happilly when under full use??? However, that said, once the PC HAS been running (ie warm), it always seems to restart without problems.

I'm sure its not simply that its booting and I just can't see it on screen as there's no event record of windows starting on my "failed" starts.

Next time it fails I'll recheck the card seating/clean contacts and meanwhile I'll have a look to see if there are any MB LEDS and get back.

Any other ideas also greatly appreciated.

  DieSse 20:01 13 Jan 2008

I've had PSUs that struggle when they're cold, but fine when warmed up - one took up to 15 mins, and gave many weird problems during that time, even though the nominal rating was more than good enough.

So don't rule out the PSU.

But my money would be in the graphics area right now.

  DieSse 20:03 13 Jan 2008

Forgot to add - normally you would expect to have a screen display during the POST and before the beep. So lack of a display at that time leads me to think it's the graphics not coming on soon enough. This could well stop the complete boot-up.

  Lightchop 20:19 13 Jan 2008

Had similar issues with a couple of old laptops I was messing around with once. Turned out to be a faulty interface between mobo and screen, the lack of (or faulty) display not allowing POST to complete.

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