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Archived This topic has been archived. Information and links in this thread may no longer be available or relevant. If you have a question create a new topic by clicking here and select the appropriate board.
HP Recommended
HP ProBook 450G0
Linux

Hi all,

this is not my computer: I am a student and in the free time I fix computers to earn some money. I am not a professional and patented IT technician, but all the people I assisted are happy with my work, and I dismount and mount computers since I was child at the times of 486 cpu and Dos.

A guy gave me an HP Probook 450 G0; he reported that the computer didn't boot anymore, and he already tried with another technician and he said that the motherboard or the gpu was broken... a sentence that says all and nothing because is the typical sentence one says when the problem is not understood.

After some tests, I realized that once in a while the computer did boot, something like one time in five.

The other times, the only sign was a constant blinking of the white led installed in the caps lock key. This is a case not covered in the page about error codes: https://support.hp.com/us-en/document/c01732674

I moved the dimm module on the other slot (the computer has only one 4GB module) and then I got it working 100% of times (tried for many times).

Windows 10 was broken and considered that the guy uses Linux (me too and I am a Linux expert) I removed Windows and installed Linux.

After that, I used the computer for a couple of days, 5 or 6 startups circa. Then, I decided to perform some stress test, so I connected the computer to the grid of a University that perform bioinformatics researches with a distributed computing system. The computer worked for 6 days straight, no error at all (every result is checked by another machine), temperature well below the limits.

Then, while the computer was perfectly working, I turned it off but at the next startup the problem reappeared but in a worst form: now it is impossible to get the computer to boot even after 10 or 15 attempts. I tried to move the dimm between the slots, clean them, remove hard disk, wi-fi card, disconnect the CMOS battery to reset the bios and so on. Nothing. The only news is that sometimes (few times) instead of get the continuous blinking I get two (led) "beeps", then pause and then another two beeps, that means according to the page I mentioned before BIOS error. I cannot try other DDR3 modules at the moment because I have only DDR2 modules here.

The weird thing is that I cannot perform any of the procedures shown in that page, such as WIN+B, WIN+V, holding power 12 sec to reset controllers... because the computer is ALWAYS on, I can turn it off only removing the plug or the battery but then as soon as a power source is connected it switches on and it is impossible to switch it off using the power button.

 

I don't know what to do and I am very confused by such an error. It's evident that the system is fully working, it is impossible that something is broken in CPU/RAM/Motherboard because the computer did computationally intensive tasks for several days, any bad memory cell, problem with clock and so on would have appeared.

The problem it's only in the startup, before the POST, but it's strange that is the bios EEPROM because it worked and it's unlikely that an EEPROM fails in that way. Or it works, or it doesn't work this is really a strange behaviour. I'd really like to understand what's happening also for my curiosity, I don't care about the money because I have already fixed other computers for him and this HP is more a "plus" considered that he was ready to scrap it.

Also I am a bit upset that a laptop can die in this way, this is rather new and very expensive... I have laptops of the 90s still working. I have the suspect that it is some "stupid" thing, like some security feature or top-level software issue because this is a strange way for electronics to fail and also for easy softwares.

Best regards,

sorry for english and lenght

 

 

 

 

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