Yes, it's another computer help thread!

[Aedilred]

Just over a year ago, I moved house, and in the process did something to my computer that has broken it horribly. For a week or so I was able to coax it into life, but it would quickly turn itself off, and now it won't turn on at all.

It's a home-built machine; I put it together with help from a computer scientist friend, who sadly is no longer available to assist with the repair (long story). I'm confident I can switch out any hardware that's malfunctioning, but first I need to know which piece it is, and I'm also not all that confident that I can do the necessary software wizardry afterwards if it turns out to be something major (which it probably is).

I have checked the RAM and the PSU and neither of those is the problem. The hard drive may be broken, but it keeps malfunctioning even with a brand new one, so there must be something else. This suggests, rather painfully, that it's either the motherboard or the CPU. The motherboard seems more likely but I don't know how to check.

What I'd like advice about, then, is roughly: How would I go about testing which it is? How difficult would it be to replace one but not the other? And if I have to replace either, would my old installation still work or would I have to reload the OS and rip the files I need from the old HD?

[factotum]

You've been leaving this problem for a year? :smallconfused:

Anyway, I assume you've done the first troubleshooting step of making sure everything is securely seated, given that things could have got shaken loose in the move? This is especially important with the CPU heatsink, because if that's loose the CPU will rapidly overheat and the computer will shut itself down to prevent damage.

[Aedilred]

Yeah, I've been leaving it a while. The place I moved into was tiny, and I don't have the space to open the machine up and work on it. Bits and pieces are ok, but I don't want to be dismantling it altogether in this house. I'm moving soon into somewhere where I will be able to, though, so I'm keen to get it up and running as soon as I move.

As far as I could tell, everything was seated properly last time I checked, although that was a while ago.

[Odentin]

Check the Front Panel connectors. I was having this problem as well when I moved. They can pop off easily, and if they short out or disconnect suddenly, they'll trick the system into turning itself of again and again.

[Erloas]

First question is what is it doing and what is it not doing?

It sounds like it won't turn on at all most of the time but it will turn on sometimes? Is it getting loaded into Windows ever or does it fail before that? Does the screen come on, just sometimes?

[factotum]

Also, when you say it doesn't turn on, do the fans give a sort of half-kick when you press the power and then stop, or does nothing at all happen?

[Aedilred]

It seemed to get worse as time went on (over the space of a few days), which is what led me to suspect it might be something to do with the CPU.

Initially it worked OK; it would start up and log in, then after half an hour or so, shut down without warning. Eventually this started happening before it would log me in. On a couple of occasions I managed to get into setup and this indicated that the installation was corrupted. I tried to install Fedora into clean space to work on the problem, but it shut down halfway through that installation. I replaced the HD, and suffered the same problem with both Windows (XP) and Fedora; the machine would turn itself off before the drive could be partitioned.

The last couple of times I tried to load it from the original HD it would usually get to POST and then die. Once or twice it did nothing at all, as far as I could tell, and after that I gave up trying to fix it for the time being, for fear of doing further damage. Something I did notice on the last couple of occasions that it begun to start up was that not all the fans engaged, although they were all properly connected- I don't know whether this was because of a problem or simply because they weren't all needed, though. The CPU fan seemed to be working fine.

All the internal connections appear to be fine- or at least connected as well as they can be.

[Erloas]

How old is this computer? Is it a Dell, Compaq, etc. or something a friend or local shop built?

I really doubt it is the CPU, they virtually never go out if you aren't heavily OCing. Getting one DOA is a lot more common then them dieing after use. I also wouldn't expect it to get progressively worse, rather it would die all at once or crash at very specific times.

Do the fans that do come on seem to be running at the same speed all the time? I know not all fans are on controllers, but about the only one that will shut the computer down is the processor fan, and those are usually speed controlled. If the heatsink has came up for any reason that could cause a lot of those problems, and if its came off even more it might not take more then a couple seconds for the processor to get to shutdown temperatures. My aunts computer was having problems and it was because one of the legs on the heatsink broke and it was doing something similar to that. I was able to superglue the leg back together and get it running fine.


What I'm thinking is more likely is that the power supply is going bad. Especially if its a cheap brand, low power, and several years old. It is also possible it is the power regulating circuitry on the motherboard itself, though it tends to be the power supply more often then not. Being one of the only highly analog circuits, its one of the few components that is likely to progressively go out rather then completely die all at once.
Do you have onboard video, a video card, or both? If you have both you might try removing the video card and running straight off the motherboard, it eliminates the video card as a possibility and it reduces your power requirements by quite a bit, which might temporarily help if it is the power supply.

[factotum]

It could be CPU overheating because of a dodgy heatsink connection, a bad PSU as Erloas mentions, or a motherboard fault. One thing to check: have a look at all the capacitors on the motherboard, especially the ones around the CPU. If any of them have a bulging top, and *especially* if you see any brown gunk on them, it means the capacitors have gone and it's motherboard replacement time. (We had a bunch of faulty Dell 270s at my old place of work that failed in this way, and the symptoms were very similar to what you describe).

[Aedilred]

How old is this computer? Is it a Dell, Compaq, etc. or something a friend or local shop built?
A friend built it for me; the components were all pretty high-end at point of purchase (just under three years ago).


What I'm thinking is more likely is that the power supply is going bad. Especially if its a cheap brand, low power, and several years old. It is also possible it is the power regulating circuitry on the motherboard itself, though it tends to be the power supply more often then not.
Yeah, that was my first thought. I'd already had to replace one PSU, but the new one should have been fine... the replacement didn't fix the problem, so I'm pretty sure it's something else.



Do the fans that do come on seem to be running at the same speed all the time? I know not all fans are on controllers, but about the only one that will shut the computer down is the processor fan, and those are usually speed controlled. If the heatsink has came up for any reason that could cause a lot of those problems, and if its came off even more it might not take more then a couple seconds for the processor to get to shutdown temperatures. My aunts computer was having problems and it was because one of the legs on the heatsink broke and it was doing something similar to that. I was able to superglue the leg back together and get it running fine.
I'll check that; I'll also take a look at the motherboard capacitors.

[Renegade Paladin]

I'd suspect the hard drive, actually. I had a hard drive die on me during the move last time I moved; fortunately it was a secondary and my computer worked fine without it. I just lost a lot of non-essential data.

[factotum]

I've never had a hard drive failure that prevented the computer even switching on... :smallconfused:

[Zeb The Troll]

That plus he said that he's replaced the HDD already.

My first thought was power supply, but since that's also been recently replaced, that seems less likely also.

However, if the last power supply was bad, it could have, over time, mucked up the motherboard circuitry before going south forever.

I'm thinking, at this point, that it's time to investigate the heat sink on the processor if you haven't done so already. I know it was mentioned early on, but I didn't see any indication that you'd looked into it yet.

[IonDragon]

You've been leaving this problem for a year? :smallconfused:

Anyway, I assume you've done the first troubleshooting step of making sure everything is securely seated, given that things could have got shaken loose in the move? This is especially important with the CPU heatsink, because if that's loose the CPU will rapidly overheat and the computer will shut itself down to prevent damage.

This. It sounds most like you had some sort of problem with your fan if the computer was running and would shut down at increasingly frequent intervals. Check the capacitors, if any of them are popped up or bubbling over you need a new motherboard and may need a new CPU, but you won't be able to tell that until you have a functional motherboard that you can put it into.

[Aedilred]

Ok; I've now moved and had a chance to examine the computer properly. The motherboard capacitors all seem fine; there were some loose connections between various cables, although these might have popped out in the latest move. All else seems fine and dandy physically. All the fans work when I turn it on, and it no longer seems to turn itself off quite as easily.

The original HDD is screwed, though. Any attempt to load from it leads to blue-screens and a restart. I'm trying to load XP onto the new HDD and boot from there, but it keeps telling me that I haven't got any XP-compatible partitions, even though I'm newly partitioning the drive during the installation (?!) so I'm not sure what's going on there.

[IonDragon]

If if had been a loose power cable to one fan or another then it could have caused damage you wouldn't be able to see. A boot diagnostic CD would be well advised. Boot your computer from the CD and it will bypass the HDD completely, run a RAM diagnostic test, then do the same for your CPU, though the RAM test will help you tell if it's a critical problem with the CPU.

If the RAM test gives you errors then you have a RAM problem. If the test crashes you have a problem either in RAM or elsewhere, likely elsewhere.

Most computers places have a good 2 week return policy, often no questions asked. If you can afford the parts for a new computer now, get the parts you need, and diagnose the parts you have by replacing them one by one; MoBo, CPU, PSU, RAM.