[phillpower2]

The computer not shutting down when you press and hold the case power button means one of two things, the case switch is broken or the MB is bad, the latter includes something shorting out.

 

For now we need to wait on the outcome of jump starting the PSU and then checking the temperature of the CPU, you saying that there was not much thermal compound on the CPU when you removed the heatsink was not a good sign as it could mean that the CPU had overheated.

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Sorry for the misunderstanding regarding the Thermal Compound but when I wrote that I ‘found there was no TC left’, I meant that the syringe I had in the cupboard turned out to be empty, hence ordering more, not that there was little on the cpu itself.

Having said that I have done the cpu test as you described and no heat to my finger was detectable. This was perhaps half second on/off. I noticed a small red light labelled CPU LED on constant.

 

Shorting the ps pins booted the PC but did not respond to turning off by the same method.

[Ste]

Sorry for the misunderstanding regarding the Thermal Compound but when I wrote that I ‘found there was no TC left’, I meant that the syringe I had in the cupboard turned out to be empty, hence ordering more, not that there was little on the cpu itself.

Having said that I have done the cpu test as you described and no heat to my finger was detectable. This was perhaps half second on/off. I noticed a small red light labelled CPU LED on constant.

 

Shorting the ps pins booted the PC but did not respond to turning off by the same method.

[phillpower2]

TC info acknowledged 

 

I take it that you mean shorting the pins activated the PSU, have to ask for clarity as a computer has not successfully booted up until an operating system is actually running.

 

The CPU socket on your MB is fed by an 8 pin 12V power connector and being that you mention that the CPU did not get hot I would suggest that you check the 8 pin 12V power connector on the MB for any signs of damage such as scorching etc, you should also check the MB for any bad caps, to help with checking the caps see the info here the images to the right in particular.

[Ste]

Hi, yes, it activated the PSU.

 

No scorching around the CPU power connector and after double checking all over the board I don’t see any distortion/swelling or anything oozing from the caps which all look vertical to the MB.

[phillpower2]

Thanks for clarifying 

 

The last real test that you can do now before thinking about either getting the system tested or you swapping in parts yourself is to try the heat test on the CPU a second time, this time though have your finger gently on the top of the CPU when you activate the PSU, if the CPU starts getting hot quickly remove your finger and power down.

 

Depending on the outcome of the second CPU heat test, if the CPU stays cold you need to get the CPU socket tested with a multi meter as that is the only way to check if the CPU socket is getting power.

 

Just a fyi, MBs have a higher failure rate than CPUs and neither tend to just give up working for no reason or without giving some tell tale signs first so can I ask how and when you first encountered the no signal message, were you using the computer at the time and the screen went black, did you power up and get a black screen or had you been using the computer but left it unattended and come back to a black screen etc, knowing the answer to this just might give us a clue.

[Ste]

Hi, the ‘no signal’ message appeared on the morning boot up; there had been no problems the day before.

 

I extended the time with the power on whilst holding my finger on the CPU and it did not heat up. Am I right in thinking that it is back to ‘the CPU or the main board’ choice, and that the CPU could have failed or because of a fault with the main board no power is getting to the PCU?

 

 I would prefer not to pay labour costs and spend time taking it to the shop if possible but does that leave me with the choice of replacing the CPU  or the main board, (there is a CPU for sale –Seller Refurbished-‘Retail Boxed AMD FX 8320 8x Core 3.50GHz Socket AM3+ CPU With AMD Wraith Cooler’ for £79 with a six months warranty)?

 

Again, I am only asking an opinion here; I suppose it’s a hard one, especially as you say MBs have a higher failure rate but am I right in assessing my situation, as I am willing to take a chance on the CPU but maybe I could get an estimate to have the MB tested first? I'll maybe see what you think before deciding.

[phillpower2]

Hello Ste,

 

It sounds like electrical damage of some sort then, you normally get overheating type problems if a CPU is having problems and problems starting up when the board is going wonky.

 

Any sparky will have a multi meter and so should be able to test your CPU socket for you, avoid the likes of PC World and the likes.

 

I may not be around tomorrow and possibly Wednesday but will try and check in if I can.

[Ste]

Hi, well I’m going into drastic mode, I’ve ordered the cpu as I don’t know any sparkies, especially none that work for free.

 

If it doesn’t work with the new cpu I’ll bite the bullet and go for a new main board. Hopefully it will work by then. I can always sell the old cpu. I’ll get back when I’ve fitted it.

[phillpower2]

I have done the cpu test as you described and no heat to my finger was detectable. This was perhaps half second on/off. I noticed a small red light labelled CPU LED on constant.

 

 

Suggestion, before fitting the replacement CPU, disconnect the case power button connection from the MB as a precaution, you know your PC better than us and if the power button staying lit up looked wrong to you then it most likely is.

[Ste]

Hi, after buying the CPU the seller communicated with me about fitting it and in the conversation I gave a short description of what I thought was my dilemma, i.e. a possible problem with the CPU or the main board. He agreed with you that it was more likely to be the main board.

Because of the different possibilities and I must admit, my impatience, as I do need to get the main system going again, I purchased a main board from the same seller, also refurbished with a six months warranty. (The same board as mine).

I thought that would cover everything, but as you now mention the switch again as a possible problem, it concerns me if it could harm the new CPU or MB?

 

When the new CPU is installed, do you suggest I try to boot the system by shorting the pins as before or is your suggestion just referring to the ‘fitting’ of the CPU whilst unplugged? If the system boots by that method, would then trying the switch as normal have a risk to the new CPU (or MB if there is no success with the new CPU)?

 

Are switches replaceable or would a faulty one mean buying a new case? Sorry all this is dragging out but I would like to be as clear as possible.

[phillpower2]

I never assemble any new build or upgrade inside the case to begin with as it is far better to check that everything works first + if anything is faulty you will find it along the way, often referred to as a barebones set up or breadboarding, below are my canned instructions;

 

Do a barebones set-up on a piece of cardboard (make sure it is larger than the MB) only connect the PSU, the GFX card, screen, 1 stick of RAM and the keyboard.

IF your MB doesn`t have a power  test switch you will then need to short out the 2 power on pins on the MB header to get the PSU to activate, you can use a small flat bladed screwdriver or a paper clip bent into a U shape, this is perfectly safe if you do not touch anything else, the idea is to see if we can get a BIOS screen if you do you can then add one component at a time.

 

You must power down and remove the power cord from the wall before adding another component, 

[Ste]

Best Answer

HI, well, after receiving both the new CPU and main board I first of all tried the new CPU on the original board which did not solve the problem. From this I deducted that it was after all the main board. I then followed your instructions and found that the new board and CPU posted. I then added the peripherals and I’m up and running again.

 

Now I have problems with accessing the other two internal drives which are not recognised-‘invalid’ but that would be another post if I don’t get anywhere with ‘Testdisk’ which I’m about to check out.

I’m very grateful for your support with this problem and I’ve learned a few things along the road. Thanks.

[phillpower2]

Glad to hear that you are up and running and thanks for letting us know 

 

Too late now but you could have tried the original CPU in the replacement board, had you been able to confirm that the CPU was working you could have sold it on to recoup some of your cash.

 

Marked your thread as solved but before you go can you update us on the power button being lit up with the previous MB and CPU, is it still the same etc.

 

You are welcome btw 

[Ste]

Hi, no the power button on this case consists of two vertical slits. When the computer is running normally one slit stays on constantly and the other occasionally flashes which I would guess is to do with internal processes. As I mentioned when there was a problem both lights where on permanently.

I can't find anything obvious withe the old main board only that I noticed some dust had somehow slipped under the heat sink at one edge, which was actually quite tight on the CPU so that seemed odd, but as dust in non-conductive I don't suppose that was the problem.

 

Yes, I meant to test the other CPU, would swapping it in order to see if it works, mess things up? Sorry to go on, a simple yes/no would suffice. Thanks again.

[phillpower2]

Thanks for getting back to us regarding the case lights, being that they are back to normal I would suspect them staying on with the previous set up the system was locking up when the CPU was being checked during the power on self test.

 

I can't find anything obvious withe the old main board only that I noticed some dust had somehow slipped under the heat sink at one edge, which was actually quite tight on the CPU so that seemed odd, but as dust in non-conductive I don't suppose that was the problem

 

 

Hard to say really but just so you are aware dust can be conductive as it depends on whether or not there are any metallic particles in the said dust, any dust can cause a static and/or a build up of heat as well.

 

Now that you are up and running I would be loath to undo your work, box the original CPU up and store it somewhere safe, you may get around to being able to test it some day.