I have an old PC running XP which has started to lock up in a way that I can’t diagnose. I can usually figure this sort of thing out because one way or another I can get a clue that is google-able that I can use to track down the probable cause and solution.
What is happening is that the machine just locks up completely. From the moment the problem starts you can’t do anything except perhaps minimise and maximise screens, but after perhaps 20 seconds you can’t even do that. Ctrl-Alt-Del won’t work, nothing works at all. Just a complete freeze. All you can do is a hard power off.
It seems to happen at random intervals, sometimes a few minutes after turning the PC on, but sometimes it may run fine for hours.
I can’t pin it on any particular piece of software, it has happened when using a wide variety of programs.
I’ve been amusing myself by fixing PC problems like this for years, but there has always been something that gives me a clue as to where to start, but not this time.
The first thing to look at is heat, although the classic symptom of a heat problem is that it runs for a while and crashes. Your problem sounds a bit more random than that. Heat problems are also more likely to show up while you are doing something CPU-intensive, like playing a game or running some high CPU usage program. Still, might not be a bad idea to check all of your fans to make sure they are spinning, and you might want to get some compressed air and blow all the dust out of your system (don’t use a vacuum unless it is specifically made for electronics, or static from the vacuum may kill the PC).
Another thing to try is reseating the CPU, memory, and any I/O cards you may have in the machine. I’ve had very strange problems just from things shaking loose due to vibration.
If you think you can reproduce it reasonably reliably, bring up the task manager and look at all of the tasks running, and sort them by CPU usage. Leave the task manager running over on the side of the screen while you do other things. When things start to go wonky, look to see if anything is hogging up the CPU.
Fans are OK and it’s midwinter here (and our house is unheated) and it doesn’t seem to correlate to intensive usage. I suspect not heat.
Re-seating I could go for but it is going to be a damn slow process, given that it is such an intermittent problem. I won’t know if I’m doing any good or not. I’m also a bit sceptical of this because if something is coming unseated, how come immediately afterward on reboot everything is fine? Nonetheless I’ll try this.
I like the last point. I’ll just make a habit of keeping task manager on all the time where I can see it even during a crash.
After a power up, what is the shortest period that this has taken to occur? You say “a few minutes”, but are we saying 3 or 30? If the former it can’t really be heat, if the latter it might be. Google for and install Speedfan to monitor temps.
After that I’d say the most likely suspects (in no particular order) would be CPU, system memory, power supply, video board, motherboard.
The timing varies. Actually, now that I think about it, I suspect it either happens in the first ten or fifteen minutes or it doesn’t occur for ages. I might keep an eye on that point.
The M/B etc are clean as a whistle, I replaced the M/B about six months back and cleaned it all out then and our house is pretty dust free (no carpets or rugs), no soft furnishings in the relevant room. And to answer your next question, no this didn’t start happening straight after I replaced the M/B. It’s been going fine until a week or two ago.
Safe mode. Good idea. I’ll try that.
The caps are all fine.
Ram has been a problem in the past, though when it’s been a problem it’s always been a problem on POST and not while the PC is running. Could be that though.
Test the RAM with memtest86. “Random” errors can sometimes be caused by a particular memory address (even just one bit) that isn’t reading back what you wrote to it, which would manifest differently every time depending on what that address is being used for.
[QUOTE=Princhester;13967682
Ram has been a problem in the past, though when it’s been a problem it’s always been a problem on POST and not while the PC is running. Could be that though.[/QUOTE]
Given that new info, I wouldn’t bother with memtest86 (IMO software-based memory testers are nearly useless). If it’s errorred in POST even once, replace system memory.
ETA: have you reseated everything attached to the MB?
When I say memory has errored in the past I mean that probably more than six months ago, the POST beeps indicated a memory problem which re-seating immediately fixed. I doubt that problem is related to the present problem.
As already mentioned re-seat ALL connections. Apart from memory and graphic cards and the like don’t forget the data and power connections for the drives and any power connection plugs say for fans.
Follow all the power connections from the power supply to the motherboard and clean and re-seat these all as well.
If all that does not fix the problem you probably need a new power supply.
I once had an identical problem and did all connection cleaning and ran drive and memory diagnostics for a for hours but in the end a new power supply was the only thing that fixed it.
I intermittently have the same problem but as far as I can tell it only happens when I have left BitComet running and I am downloading something. I come back to find all the windows looking OK but get no mouse or keyboard responses and have to cold boot.
Have you checked the event log for entries when the freeze ups occur? Even if it’s a hardware issue (which I assume), it may give you valuable information for troubleshooting.
Wheeljack hit the nail on the head for a rather common problem. Askance missed the boat, as post doesn’t hit the memory hard. Run memtest86 on it, if it fails, run it again after noting where it failed. If the failure is randomly and massively different, note it. If it’s fairly close to the same location or the same location each time, it’s the RAM. If it’s REALLY all over the place, it’s the power supply.
Yes, the power supply. Those capacitors mentioned elsewhere are even MORE heavily in the power supply. I’ve had bad power supplies eat hard drives for lunch and even damage motherboards over time and wreak havoc in all manner of things in between. A power supply partial failure can emulate CPU failure, RAM failure and, as mentioned, cause hard drive failure. Damned if I know WHY, as the damned thing is supposed to park when power loss occurs. I suspect CPU “confusion” due to an error state from the supply, where the logic is +5V or 0V, it get +2.5V or a bit less, which is indeterminate and confusing to many logic circuits.
But then, I’m qualified to actually diagnose a motherboard to component level as a CET.
And 20+ years experience.
Looking at the motherboard capacitors is a good idea too, ESPECIALLY any near a heat sink (aluminum thing that is on a chip or transistor). Google electrolytic capacitor, select image for pictures of them. You’ll figure them out REAL quick.
Hint, the TOP may not mushroom out, they’re scored to crack open, rather than explode. But, the bottom will push out the rubber “cork” sealing the unit.
A simple way of explaining an electrolytic capacitor is, a roll of paper, with a thin foil on either side of that paper, insulated by that paper. That paper is “filled” with an chemical that increases insulation value of the paper. That compound evaporates over time and the capacitor leaks current. Capacitors STORE charge, that charge is easily explained as voltage (ignoring a bunch of math). Leakage is normal in electrolytic capacitors, which is why we don’t use them much (save some really new super capacitors in some flashlights and other circuits) as a “battery”. Again, a buttload of math. Now, a LOT of leakage causes massive amounts of the eletrolyte to evaporate rapidly.
Slightly “rapid”, the top or bottom bulges. RAPID, the thing explodes, stinks up the room and fills the circuit board and case with “popcorn” (well, it sort of LOOKS like small popcorn).
OK, enough of basic electronics goobered down. As I said, there is some math behind it…
As to the stuff about basic electronics, it’s been several months since I last designed and built an electronics project from scratch, so if after 30 plus years of playing around in the field I do happen to forget what an electrolytic cap looks like I’ll be sure to re-read your post.