Monitor suddenly not recognising PC

Hi there,

             I was switching around some plugs in sockets yesterday when I accidently unplugged my pc tower (it was turned off). When I realised I had unplugged the wrong thing I put it straight back in the gang extension lead socket. There was a tiny spark when I did this - no bigger than the spark you occasionally get when plugging something in - and my PC suddenly sprang to life and switched itself on. I was surprised by this and quickly held down the power button on the tower to turn it off again. 

Once I had finished moving things, I switched the PC on again but the monitor was now not recognising the PC at all and was acting like it was receiving no input, black screen etc (I then checked the monitor with another PC and it worked fine). Also, the tower now has small green '3' and '4' lights lit up on the front of it….I'm pretty sure this wasn't the case before.

Any help or advice appreciated

Jen x

That does not sound good, and the way you accept a "spark" as being normal concerns me, what you describe the PC doing strongly suggests  a power surge, more so with your talk of a spark, obviously we are not there, and can only go on what we are told, but this is the only thing that comes into mind given your description of events.

But lets check something and see what happens, but while moving things around did you move\plug anything at the rear of the PC ?

The only other possible that comes to mind is when this is done (and I hope this is the case here), is the video connection coming loose\unseated, but only if it's a video card, as opposed to on-board video, I have seen video cards have their copper terminal that inserts into the slot on the board slightly exposed, it can happen when sideways force is placed on the monitor lead.

The card doesn't need to be out much to start playing up, or stop working altogether, to check this you will need to turn off the PC, remove the mains lead (see note at end of this about putting back), turn off the PSU if it has a dedicated power switch, then open the side of the case, lay it on it's side, visually look to see if you can see the copper terminal showing from the slot, if you can it starts to support this idea, but if you do or don't, it's still worth doing this as your there, touch the side of the case to start, then gently, but firmly push the card into the slot, just make sure it is securely seated.

Then put the side back on, stand it up, now connect all but power, (note; before plugging in power, turn off the wall switch, then plug it in, and turn the wall switch on), then if the PSU has a switch, turn that back on last, hopefully this will minimise the risk of surges.

It is highly recommended to use surge protection, a UPS device is the ideal, but at a minimum use a surge protector, it won't do as good a job, but it's way better than nothing.

Obviously this is aimed at those comfortable\experienced at doing this kind of thing, if you are not comfortable, or want more detailed instructions please feel free to ask, but see what this does and we can go from there, hope this helps.

But on a side note, I am concerned over your acceptance of sparks being the norm, does this happen to every socket in your place ?

And does it matter what you actually plug in, e.g. high power\demanding devices, or does it make no difference what is plugged in ?

What are the chances of getting your supply checked out ?

Hi, thanks a lot for helping me.

Sorry, I'm afraid I may have chosen my words rather poorly when writing my original message (it was posted at about 3 in the morning and I was very tired!). There wasn't a 'spark' as such….just that occasional very slight crackle you can get when putting a plug into any socket when the power switch is left on. I understand and appreciate how you could be concerned when I read back over my post and again I'm sorry for being misleading…but I really dont think there is cause for concern with the electrics and power in the house.

I followed your instructions about the videocard but it seemed to be firmly in place and the copper terminal was not exposed.

I did a bit of searching to try and find out what the green '3' and '4' lights on the tower meant and found the online manual for my PC model (linked a bottom). On page 21 it suggests this means that…

Well I do know you can get such a "spark" or crackle when putting plug in or out, mainly when you reach that biting point where the power starts to connect, usually apparent if the plug seems to be put in slowly, or more likely gets a bit tight\stuck part way in\out, it's the power arcing over, but to sensitive equipment like a PC, it can still cause a surge.

Using a power switch to turn on\off while putting the plug in or out is a safer way to go, but surge protection is still highly suggested, because you can't see the surge(s) coming, nor power spikes and brown outs and the like, so it's money well spent.

Now the following is a copy and paste of something I wrote in another thread that covers testing ram, and it's the same process no matter what you are doing it for, but I wrote it in such a way that anyone who would follow it (not in the same position as the topic owner), I covered all the bases, so please don't think I am under estimating you in doing this.

 

Right the test you have run is to test the ram (memory), not the hard drive or anything else, but if you have reason to wonder about the hard drive we can set you up to scan that for peace of mind if you wish, but given multiple issues all arising from power, I suggest dealing with each in turn, it will be easier to manage and not start getting mixed up.

 

The fact the ram had no faults found, doesn't mean they are good, so the next step to try is swapping stick around, taking some out and running in-between long enough to get the feeling if you system feels like it used to be, but this is very possibly going to be time consuming, and repetitive, but it's a good way to see if anything shows up, but you are going to have to be methodical in doing this, so pen and paper is advised to note each combination you try.

 

First the safety rules, whenever you go to go into the case, turn OFF the mains, AND remove the plug, next if the PSU has a switch, turn that off as well, it is the mains power supplied by a kettle lead, and if there is a switch it will be close to where the cable plugs in, a major factor to remember is that static electricity can kill ram as well as other parts, and it only takes a couple of steps to generate enough static to damage something.

 

So before you touch anything, touch the side of the case (the chassis), this should eliminate any static, but make touching the case like this the 1st thing you do before touching anything inside, and do this every time you go to touch something, even if you have only taken a couple of steps, after you have done each step of what we have to do inside the case, put the side back on, but you only need to use 1 screw (keep the others safe though), then turn it all back on, this is the cycle you need to do every time, it's to keep you safe, and the parts.

 

Now open the side of the case, there should be 2, possibly 3 screws that hold it on, if they are big you should be able to undo them by hand, but if they look like any other screw then you will need a screwdriver to undo them, they will be on the rear of the case, on the lip of the side that comes round the back of the frame, the lip is maybe quarter of an inch, only undo the 2 or 3 screws in that lip, but there are numerous other screws on the rear, but it is only these ones on the lip that needs to be undone.

 

With the screws out, you should be able to remove the side, often it needs to be slid backward while flush, this part "may" be easier to do on it's side, once it has loosened, you may be able to straight lift it off, or you may need to "open" it like a door, most of the time it will lift off, it all depends on the case, once removed you will be able to see inside the case, and have access to all the parts.

 

First thing is take note of everything, but touch nothing yet, the ram will be long rectangle shaped sticks with chips down their sides, it will be close to the heatsink, which is a big block of metal with a fan on top of it, take note of how many sticks there are, and how many slots there are, the slots are colour coded (usually) lengths of plastic that the ram slots into.

 

It will also help me to know the make\model of the motherboard (that's the big PCB panel that everything's plugged into), this info is usually printed on the board, and take note if it says a revision number, e.g. Rev 2, if you can't see this clearly then we can find out by running another scan, but I would like to know what we are dealing with to make sure we get it right.

 

Now starts the pen and paper bit  write on the bit of paper Slot 1, Slot 2, Slot 3, Slot 4; this assumes there are 4 sticks of ram, but 12gig is not a figure that I associate with 4 sticks, which is partly why it would help to know what board we are dealing with.

Slot 1 is the slot nearest the heatsink, with Slot 4 being furthest from it, as you move these sticks make sure you keep them on the piece of paper against the slot they came from, when ram states getting swapped around, it is very easy to lose track of what came from where, so this is important, and I don't know if you have anyone else around, or pets, make sure they are unable to disturb this paper and mix up the ram.

I hope this helps, and feel free to ask anything you may want clarifying.

Ok, I've finally had a chance to follow that.

The motherboard model is CN-0FJ030-70821-62N-G0IJ and the revision number is REV A00.

I have two sticks of 1gb RAM. They are in slots DIMM_1 and DIMM_2.

Should I just try each of the sticks by themselves in all 4 slots?? Or should I try all the possible combinations of both sticks in slots together?? Or both of the above??

Thanks,

Jen x

I can't find info on that board model you supplied, although it suggests it may be a Dell XPS system you have, can you get and run Speccy (free version) please, and let me know what that say's your board is, the 1st screen is a summary of the entire system which should have all we need, but if you click Motherboard on the left, it will show even more detail, but ultimately all I need is the Motherboard make\model, and any revision number, I can then see what it say's about the boards slots.

Now as to testing, the suggestion is that 1, or multiple sticks of ram may be the cause of your problem from what you have found, as you only have 2 sticks, you simply test them 1 at a time, in a slot at a time, keeping track of what each stick is by using the method I detailed above, so you know which stick is from where.

So just test them on their own, in all slots, and take note of what you feel about the systems performance (if it's running smoother or the like), but bare in mind that using half the ram will slow you down a bit, most noticeable when running at load (heavy applications or procedures running), but you will be noting if it seems easier going from what your used to of late.

Once you have done that let us know what you find, make sure you specifically note if a specific stick\slot plays up, but let me know the finding's of Speccy as soon as you have them, then I can check out the correct slots to use, to optimise the ram's performance, should this be inconclusive, we can run another test via software, you will need a disk to burn this program to, then it will need to be run at boot, but worry about that after this is all done.

Hi,

    Ok I've tried the sticks, individually, in all 4 slots. I'm still getting no response and the monitor is still blank screen, acting like it's receiving no input etc. For this reason I have been unable to download and run the Speccy program.

Looking again at the motherboard…does this number…..'P/N: 316736100010_R01_A00'….mean anything??

Thanks,

Jen x

Then ram may not be the issue, and the part number doesn't give me enough info to properly identify the board, it just shows you have a Dell XPS 420, at least that's what comes back in searching that code, not sure why you can't download Speccy, so try and do exactly the same as above, but using  PC-Wizard (links on the right, both are the same, just created using different compression software, you only need 1 of them).

Running another scan\test overnight may show the ram's condition better, how would you feel about burning a program to disk, booting to that disk\program, and letting it run say overnight (that way you won't be without the system) ?

I have been completely unable to use the PC in question since my original problem. The tower switches on but I've had a blank/off screen ever since this happened. Therefore I cant download or run anything on the system at the moment. I've been posting here on my laptop.

Thanks

Jen x

That sounds bad, it strongly suggests a bad video card, you said above the monitor works fine with other systems, is that still true ?

Just want to make sure nothings changed there, but the next question is do you have a spare video card to try ? Or can you put your card in another system to test ? Or both ?

I'm hesitant to say you need a new card until we can confirm what this card is doing, power may also be an issue, but it depends on the card for a large part of it, if it's a really high end card it can require a lot of power, or if a PSU is starting to work at less than it's proper rating (can't output enough power the card needs unlike when it was new).

A  PSU tester will help there, but it takes someone confident enough to do this as it means dealing with power inside the case, but you can get simple plug and test connectors to use for this which makes life easier for most people, but swapping a video card is the cheapest option (free) as long as you have a spare, or another system to borrow from, or a mate who is willing to let you try theirs, any chance of any of this ?

Ok, I've got another (pretty old) system that's not in use really any more. I could feasibly take the video card out of that one and try it….as long as this wouldn't possibly cause further problems??

Also, I've really never messed about inside the machinery of any computer at all before…even something as apparently straightforward as changing the video card. I take it that it's easy to do? Could you tell me how to go about it please? (excuse my ignorance  :))

Jen x

Or do you think that it's probably at the stage where I should just pay someone to fix it??

To be honest, it's probably easier to do, than explain how to, but we've all done this the "1st time" ourselves, so know exactly what your feeling, and ask away if you need to, that's what we are here for, but safety first, shut down the system(s), turn off the power switch at the wall and remove the mains lead, turn off the PSU's own switch if it has one, then remove the side, may be worth taking some pictures to help you see how the wires are connected at the start, then if one comes loose you can see where it came from, it's easy to knock things if it's a tight fit, and untidy cabling.

Once your happy you have enough pictures of all the connections inside the system, you can start removing the card, to start with remove the lead from the monitor outside of the case at the rear, then remove the securing screw (or quick release if it has these instead), once these parts are free, there is little holding the card, but do take note of the board at the rear of the card, there is likely to be a little lever, this needs to be pressed in the right direction to let the rear of the card come out of the slot, but make sure you touch the metal case before touching any parts, and repeat this every time you move to avoid static discharge.

Now before we start, can you first confirm I have the correct model of your system as mentioned above ?

And can you tell me all the info you can from the other system, with luck you can read the motherboard make\model from it, I just want to ensure it has the same type of card in it, or else it won't work.

Once we can confirm that, I can try and get some images to show certain points mentioned here to help, but you don't need to pay anyone to do this, you sound like you will be fine with the right help.

Duplicate in error, delete please.

Hello,

         Very sorry for not replying before now…I got distracted by the festive period! I eventually decided to leave it to someone who knew what they were doing and got it fixed last week. I was given a rather techy explanation which I didnt really understand a word of…but it's all good now

Thanks a lot for your help

Jen xx