[Closed] Computer/ wizards help! What's wrong with my computer?

I would go for the power supply. You could get a multimeter and see if it's actually kicking out the right voltages on startup - the added current draw of starting every motor in the PC can drag it down, which results in reluctant starting.

Useful info. Luckily my father is visiting tomorrow, so I can get him to bring his.

A bit naive, but I have never got to grips with a PC PSU. Do they output a single voltage, and if so what is it supposed to be? 12V?

Also, it was a cheap PC brand so the components are unlikely to be the highest quality...

Sounds to me like the processor is overheating or possibly reporting a higher temperature than the safe limit is set to.

You could try cleaning and re-applying a new layer of thermal paste to see if that improves things.

Remove the heatsink and fan assembly, clean off any residue from the thermal paste or pad using a lint free cloth and isopropyl alcohol (nail varnish remover will do if you have any 😉 )

Remove the processor and clean the die as above.

Apply a new layer of thermal paste and put it all back together.

edit : you could also try setting any clock speed related stuff to "auto" in your bios.

A bit naive, but I have never got to grips with a PC PSU. Do they output a single voltage, and if so what is it supposed to be? 12V?

There are a variety of 12V and 5V supplies, I believe. Google for the pinout of the powersupply connector - you'll need to test it under load.

It's a bugger of an issue, this. It could be a fault on the power supply, the motherboard, or a CPU / heat issue as Haze suggests. You could try disconnecting everything non-essential (ie, all the drives) and see if it's happier - if it boots reliably, that would point towards the PSU. In honesty though, the only way you're going to diagnose it reliably is to start swapping bits out to see if it stablises. Maybe borrow a PSU from a doner PC if possible?

There are a variety of 12V and 5V supplies, I believe. Google for the pinout of the powersupply connector - you'll need to test it under load.

Donor, not doner. A PSU out of a kebab probably won't work.

Oh,

It's also worth disconnecting / reconnecting the power connectors to the motherboard (including secondary connectors to the CPU and graphics card where appropriate).

I had a PC on the bench the other day with the same symptoms, rigged up a new PSU and it worked, refitted the old one and it carried on working and has been fine since. I can only assume that it was a slightly loose connection somewhere.

This is all very useful stuff, thank you very much! I think I will try disconnecting/reconnecting all power connections first, then try disconnecting non-essential power connections. This might isolate whether it's the PSU. If it doesn't seem like the PSU I might have a look at the processor...

Thanks once again.

PSU or memory is my guess but you've tried memory it would seem unless it's all faulty but that's exactly what mine does with dodgy memory.

The Overclocking message is because it thinks there's a fault with that because it switching off immediately it just needs told to carry on.

Doubt it's overheating given you describe it as being off and it's when you power it up add the fact it can run all day with no worries once started.

The Overclocking message is because it thinks there's a fault with that because it switching off immediately it just needs told to carry on.

Without the exact message this is a guess, but on some OC-friendly motherboards, you can end up rendering the system inoperable by overclocking it too hard. To reset it (again, on some boards) you can repeatedly power it on and off in succession several times, which tells it to reset to 'safe' values. It's possible that this is what's happening in this case, it's interpreting the failed boots as an attempt to reset OC'ed settings.

Aye that's exactly it cougar but mine will stay at the message unless I go into bios. I don't change anything just save the settings and restart.

*nods* Not saying that's the cause of the problem, just the cause of the OC message.

I understand. That would point the finger more strongly at the PSU then.

What brand / age is it by the way? Before you go swapping bits, in the days of yore Dell and a few others used PSUs and Motherboards with exactly the same connector as the ATX standard, but with all the pins jumbled round.

I suggest a quick google may be in order to check it's not non-standard.

Bought about 18 months ago, from Eclipse. Not sure what brand the PSU/motherboard are, but I suspect something cheap. Dual core Intel processor (can't remember which one).

Probably fine then. It's obviously a big faff to make a non-standard part, and even Dell have given up with it in the last few years.

Hmm, sounds like your PC gone mad

Doubt it's overheating given you describe it as being off and it's when you power it up add the fact it can run all day with no worries once started

Very true, could always clean the heatsink and die anyway to rule it out.

It'll only cost the price of a tube of paste.

If the motherboard emits a set of "beeps" on start up that means it's detected a fault and the sequence of beeps is a code which identifies the problem. Google for a list of codes.

Ok, after a Sunday afternoon spent ignoring my wife, with my head buried in my PC case, I am about ready to admit defeat.

I have now tried:

1. Adding/removing memory cards. Fault seems to occur with any combination.
2. Unplugging disk drives to reduce power load. Has no effect/fault still occurs.
3. Unplugged every power connection (apart from some very small fiddly cables, the purpose i'm not sure of) and reconnected firmly. No effect.
4. Removed the CPU heat sink and cleaned thoroughly of dust (may need to apply more thermal paste?). No effect.
5. Removed the graphics card and cleaned fan/heatsink thoroughly of dust. No effect.

I will apply some more thermal paste to the CPU, although I am skeptical that this is the issue.

If this doesn't work I think I might have to take the PC to a commercial computer repair centre/shop (recommendations?).

Otherwise I could buy a new PSU on the off chance, but it seems a bit risky?

Anyway, thank you all for your help it was very useful in bringing me this far!

Oh, and one final piece of bizarre behaviour that may help with diagnosis is that up until the computer failed, it would ocassionaly freeze if you knocked the case (still outputting to the screen), requiring a reboot.

Also, no beeps on startup.

Thanks again!

If you're anywhere near me geographically (East Lancs), I'd be happy to take a look at it for you.

Did you manage to measure the PSU voltages?

At the last place I worked, our tame electronics guru took a bog standard PC PSU to pieces. He was trying to figure out how they could build them with such cheap filtering capacitors.

Well it turns out that the capacitors are massively under-rated, with far too much current going through them, and should only be expected to last a few months of continuous use.

OK, long shot but I've seen it before - check the plastic clip that the heatsink attaches to is undamaged.

I once saw one where the heatsink was only fastened down properly on one side due to a broken clip, cue random reboots etc.

Might explain the "freeze if you knocked the case" symptom?

and should only be expected to last a few months of continuous use.

PCs generally aren't designed for continuous use, that's what servers are for. There's an expectation that they get switched off (or at least, enter standby / power-saving) occasionally.

Might explain the "freeze if you knocked the case" symptom?

To be honest, pretty much any loose connection could explain this, along with simply a particularly sensitive hard disk.

Yeah like I said though, long shot!

Thanks for the offer Cougar, but i'm down South!

Unfortunately I didn't manage to measure the PSU voltages; I couldn't get hold of a multimeter at the weekend. It's a bit annoying as it would certainly help determine whether the PSU is a problem - i'm not sure that buying a new one is sensible without confirming it as a problem first.

No mates with PCs who'd loan you one?

Well it turns out that the capacitors are massively under-rated, with far too much current going through them, and should only be expected to last a few months of continuous use

PCs can and do work for years on all the time, or almost. That must've been a crappo PSU. My in-laws typically run their PC on all the time as do many offices and other folk. Less so nowadays of course as people start to realise how much it can cost.

PCs can and do work for years on all the time, but that's not the model they're designed to run with.

+1 to the 'crappy PSU' comment though.

Ok... sorry to dredge this up again!

I bought a PSU from Maplin, on the basis that I could (hopefully) return it if it turned out that it didn't fix the problem.

I tried the new PSU (780W new vs 500W old) and got the same problems. I also tried recoating the processor with thermal paste. Again, same problems.

Not sure what to do now... I am tempted to try an old graphics card (borrowed from an old PC at work). If that doesn't change anything, then I guess it is probably the motherboard, processor, or else I damaged something else with all my faffing around. In my paranoia I worry that I could have damaged the processor or something - after all I am not an expert at handling with electronics equipment.

Oh well, thanks again and more advice welcome if anyone is feeling generous...!

Sounds like you need a new motherboard 🙁

Very long shot: have you taken the motherboard out completely? Perhaps there's something shorting it out underneath?

Ah yes, I forgot, that was on my list of 'things to try' - remove everything from motherboard, remove motherboard and check, reassemble.

Also, does anyone think that either of these could have killed the processor (cack-handedness alert...):

1. To remove the original thermal paste I used a cotton bud and some solvent. I earthed myself first (radiator), but I suppose I was worried that using a cotton bud could be a no-no...?

2. I am slightly paranoid that I might not have had the CPU heatsink properly clamped down one time when I powered up the machine. Argh. I am not sure how dangerous this is to the CPU health - presumably during start up it is not doing much and won't generate much heat, but I just don't know. It's difficult to tell because it didn't work before and doesn't work now...

Anyway, new plan of action...

1. Dissasemble/reassemble motherboard
2. If no success buy new motherboard
3. If still no success could be processor at fault(?), not sure how to test, or what the symptoms would be.

Thanks again all.

CPU death is comparatively rare compared to motherboard failure.

With the previous generation of CPUs, the Intels had fairly effective temperature management, in comparison to AMD which had none and would fail in catastrophic (and spectacular) fashion if overheated. One of the geeky websites (Tom's Hardware? Maybe) did a video demonstrating it.

With current CPUs, I'm not sure if that's still the case. I'd hope that AMD have caught up by now, but I'm a little out of date on CPUs these days so I don't know.

Ah, found the video.

Cougar.. it's lovely to have someone on STW so knowledgeable about PCs 🙂

I'm soon to upgrade my desktop I think, so might be posting on here...

Well, its an Intel CPU and looking at those videos i'm hazarding a guess that I didn't kill it! Quite a difference there...

And yes, quite a few knowledgable people here. It's been such a great help, as it would be a right pain/faff to get a professional to look at it. IME people that have an interest in computers tend to have an interest in problem solving too, which has been very handy for me!

Longshot but have you tried changing the battery on you MB?

No (not yet)... that's something else I forgot to ask: What does the battery do?

it's lovely to have someone on STW so knowledgeable about PCs

There's quite a few IT bods on here I believe.

What does the battery do?

Powers the memory that holds the settings you configure in BIOS. I can't see how that would cause the symptoms you're describing, other than if you've manually set silly figures for the processor.

If you can borrow an old graphics card from work then do so, you can then at least rule that out.

May also be worth trying a different hard drive too if you can get hold of one with an OS already installed on it?

If you do get the motherboard out, see if it will boot up whilst it's out of the case.

Like I said its longshot. I think the next stage will be to remove the MB and place it on something insulating and run it with the CPU, 1 stick of Memory and GPU and see it Posts.

have you tried turning it off and on again

If you know what MB you have, a BIOS update is worth a try - it sounds like an issue with the 'soft' power switch PCs all have these days, so it could be the motherboard (a Bios update might help, and is free to try at least) or the case (unlikely) now that you've ruled out the PSU.

definitely pull the mb though, often the little metal stand offs can be shorting something.. but thats usually more predictable.

May also be worth trying a different hard drive too if you can get hold of one with an OS already installed on it?

Pointless when you can just unplug the existing one (-:

And yeah, without seeing it first-hand it's hard to be 100%, but I'd concur that you're probably looking at a motherboard that's, well, mothered. Running it caseless is a good idea (seeing as you're going to have to remove it anyway), careful you don't knock the table with it live though.

I used to repair computers for a living (for over 20 years). Prior to that I was an MOD standard fitter/wireman.

If you remove the motherboard battery, it's worth noting all the BIOS settings first. Maybe these setting have been corrupted due to the battery being depleted. Can you get the correct settings from Eclipse to verify yours?

If you knock the machine and it's state changes, you have a loose connection which could possibly be in the form of a dry joint. It could also be a seating problem, but you say you have reseated all the boards. Did you miss anything because it didn't seem relevant?

Inspect the motherboard solder joints very carefully and also the reset/power on button assy. Try metering out the switch to see if it's actually working properly.

Dry joints can exist with the tiniest hairline crack, so take your time and look very closely. If a joint looks a bit iffy, just quickly rerun it using a well wetted clean iron (not loaded with solder though). Be quick, especially near chip capacitors, or you run the risk of them leaching.

It seems that you have eliminated the PSU by replacing it, but check the pins on the motherboard where the PSU connects. This would be the most likely place to find a dry joint responsible for causing the symptoms you describe.

Please let us know the outcome. Experience maketh a better engineer!

Whilst you're at it, check the tops of the capacitors for bulges and splits, they should be flat across and not domed. There was a massively widespread run of bad caps a few years ago.

Thanks again everyone. Latest instalment...

1. Tried the old graphics card from work, no difference. Having said that the old one was covered in dust and could have been knackered itself.

2. Removed motherboard, placed on a wooden chopping board(!) with a paper cover, and run with only 1 stick memory and GPU connected. Still dead, no change. Also inspected the motherboard, no obvious defects (to me).

Next step... buy a replacement motherboard and try that? If I get it on the net I can probably return it via distance selling regs if it turns out not to be the problem.

Ooh. Searching to see where I could get a replacement I found someone else with similar symptoms (same motherboard):

http://forums.overclockers.co.uk/showthread.php?t=18095625

Maybe I will try a different brand of motherboard...

I think at this point I'd be shopping for a new board.

[url= http://www.singletrackworld.com/forum/topic/not-buying-from-overclockerscouk-due-to-owners-politics ]Are Overclockers still racists though?[/url]

Ok, i'm shopping for a new board. My current board has an LGA775 socket and ATX form factor, I presume I just need to buy any other motherboard with the same socket and form factor.

Yeah, also check it's got enough USB ports and ethernet etc.

I can recommend Asus boards, built a few for friends & family based on these and not had one go pop yet...

+1 for Asus, they're on my shortlist.

Depending what CPU you have already, and if budget stretches, a mobo+CPU(+RAM) bundle might be a better option long-term.

For the record, I have now changed the motherboard and the computer is workign again.

My sincere thanks for all your help! It was a bit of a pain, but at least i'm a bit more confident with computer hardware now...

Good work. Glad you got it sorted.

What did you get, out of interest?

One of these: http://www.dabs.com/products/gigabyte-p43-s775-ddr2-fsb1600-sata-6JSW.html?refs=405070000-4294948008-50509

Bit of a short termist option, in that I didn't get a new processor and MB with a more modern socket, but I reckon I have a fair bit of use left in the PC yet. It was about the cheapest compatible motherboard with four memory slots from a reasonably respectable manufacturer (I have 3 x 1Gb sticks).

My old board that died was MSI.

Going from Microstar to Gigabyte is like going from Aldi to Harrods. Good choice.