Major stability problems with HP Elitebook 840 g1

[kj22017]

I know enough about computers to know that the techicians fees will cost more than the Laptop is worth.

[kj22017]

I have just performed a 4 hour full system diagnostic test from the HP UEFI software in the bios.   It took four hours and everything passed.    I just tried to add an image to prove it but my smartphone images are much higher than the 1000k maximum

[pritam2015]

                      I can understand your frustration but it may be a hardware issue as I said before. I agree your notebook is working fine over 6 hours, but your notebook is made up of semiconductor material which reduces the data transfer rate with increase in temperature which makes the notebook to work slower, but in your case overheating is not the issue and you have tried all basic fixes including clean install, hard reset. If there was any software issue then it must be fixed by clean installing the windows OS. As you performed full hardware test which took 4 hours to complete but didn't found any hardware issue, in this case, I can guess that there might be a problem with HDD. your notebook is having trouble to read data from HDD it means your HDD is crashing slowly I suggest you try to replace the HDD this may help you. (I am just guessing this is not the solution)

                      I also agree that it may be a CPU problem but it cannot be determined from here what's the issue. I hope you understand what I meant to say, only technician can help you in this case.

[RangerZ]

I realize this is a few moths old, but some things that have not been mentioned that you can try.

1 - Reset this BIOS to factory.  Before you do this note what th UEFI setting is or is not as you will probably need to match this to get the same OS to boot.

2 - Remove all the plug in stuff and reinset.  If you can clean the contacts for the memory, wireless and other cards it you can. 

3 - replace the HD or at least try a different one.

The first 2 are free and take only a few minutes to do.  If you have multiple memory try leaving one and or switching them

[kj22017]

It ended up being a faulty power supply.  After 10 days of wondering and struggling I changed power supply and it worked perfectly from then onwards.

I am astonished that a power supply can appear to provide power to a laptop yet still be malfunctioning

[RangerZ]

Well an insightful post. 

I find power supplies very frustrating.  I have not found any reasonable way to load test these devices to truly make sure thaey are functioning at anything but a voltage level. 

I happen to be dealing with a user who has now had 3 "crashes" of her laptop, in a dock.  I have suggested the first thing she do is undock the laptop and see if it recovers, however now  I think I will swap the PS and use it myself for a bit.