View Full Version : Cold boot startup problem

Rod J
25-03-2011, 01:06 PM
Hello fellow PressF1'ers,

I have been having an intermittent problem with my four year old PC which oddly seems to be related to the ambient temperature.

I usually turn my PC off at night and sometimes turn it on in the mornings. For some time now I've found if the ambient temperature is below 15C or so the PC will start up then turn off, turn back on after a second or so, then off again ... well, I've seen it do this up to 6 cycles. Sometimes, I'll try interrupting this sequence by going into the BIOS for a couple of minutes ... but occasionally it's turned off even while in the BIOS. If it gets to the Grub screen it will carry on booting as normal ... I don't think I've seen it die after this point. If it's not cold when I turn it on it behaves normally.

The HDD SMART monitoring reports everything as good (I've got two sata drives installed, 120Gb and 320Gb). Once the PC is started there is no problems at all ... everything works as it should.

For some time now if I know I want to use the PC early in the morning I'll leave it on standby the night before and no matter how cold it is it returns from standby no problem.

I suspect the power supply may be dying ... what do you think?

25-03-2011, 01:08 PM
Sounds like either a capacitor issue or a dodgy solder joint somewhere. PSU is a good place to start, do you have one you could switch out?

Rod J
25-03-2011, 01:12 PM
No, I don't have one available just now. I will have to buy a new one to eliminate the PSU as being the problem.

25-03-2011, 06:28 PM
See if you can visually identify any bad capacitors. Classic signs are a bulge (even if subtle) in the foil top of them.

A more sinister sign is a dark blob of material on the cap.
Bad caps may also stain the motherboard around themselves, a bit like an oil stain.
Caps on a lean deserve some suspicion, those with the rubber bung in the bottom partly dislodged (unevenly seated) are kaput.
More often than not it's the bigger caps, close to the width of a pencil or pen that are the culprits.

Rod J
25-03-2011, 10:45 PM
OK, thanks, I'll check out the capacitors ... if they seem OK I'll probably try another PSU.

26-03-2011, 03:02 PM
The problem could be due to the reasons already suggested, or it could be as simple as, eg, a MB connector not sitting securely in its socket. Same for a RAM module or board. Temperature fluctuations can open very small gaps in insecure connectors.

Check that everything is firmly in place before looking for more drastic solutions.

Rod J
26-03-2011, 06:58 PM
I gave my system it's annual internal dust out a couple of months ago and I checked all the components (particularly the PSU connections to the motherboard) were seated firmly. I suspected there might have been a bad connection of that sort myself. So I think I probably covered that possibility.

Thanks anyway ... it would have been a simple fix if that was all that was wrong :clap ... but it has continued to play up since then. :(

The PC started up this morning without a hitch, but the ambient temperature was about 19C.

Rod J
06-04-2011, 12:44 PM
OK, I thought I'd update this thread with a successful conclusion.

I pulled the system apart last week and thoroughly checked the motherboard capacitors, etc. All seemed fine to me. Then I pulled the PSU out and took the cover off. Sure enough, at least six of the capacitors were very swollen at the top and were obviously leaking (see pics). It was a bit of a shock to see how bad it was, I'm surprised it was still working at all. A classic case of bad capacitors I would say. PSU was CRS brand, 350W, manufactured July 2006.

I replaced it with an Enermax Tomahawk, 355W which will do for the foreseeable future.

Thanks for all your help.

06-04-2011, 01:02 PM
Glad to hear the issue has been resolved, and you've made a good choice for the replacement PSU too. :thumbs:

350w is more than enough for a basic PC these days.

Speedy Gonzales
06-04-2011, 01:05 PM
I would put something in higher than 400w. Depending on what else is in the case