Haunted PC!

[synaesthesia]

Strange one, wondering if the hive mind might have any insights!

 

We have a HP Elitedesk 800 USFF desktop which started exhibiting odd behaviour starting a couple of weeks ago. Presented automatic repair screen on reboot, and that happened out of the blue with no damage or nincompoopery from students. Brought the machine to my office to investigate, decided it was likely an SSD issue so swapped it out (NVME), rebuilt and it was happy.

For a day.

This was last week, but the joys of staff only reporting things days down the line meant I only noticed today when I went in for something else. Swore and brought it back up to my office.

HP diagnostics all pass with flying colours.

I check the CCTV in the room to see if someone was messing with it. Nope.

But I do notice it turning itself on at 01:20 the first morning it presented the issue after my initial fix.

Unprompted, no rodents treading on keys to wake it up, no other machines in the room (all identical) doing anything similar and unlikely to be power supply related as I also replaced it as part of caution the first time around.

Nothing in BIOS is screaming out to me - no remote management options like IME, no scheduled power on, nothing.

Only thing capable of waking on LAN (on purpose) is Impero and that didn't do it.

The only thing I can think of is the possibility it might be on someone's Intune or other MDM still, as it was bought as a refurb. Waking on LAN shouldn't present any problems like the auto-repair regardless, but maybe forced remote wipe commands? I'm clearly clutching at straws!

Any cunning insights welcome!

[robintech]

powercfg /sleepstudy  should tell you what did it or /waketimers  ,  /lastwake

and replace the CMOS battery as that can cause all kinds of weird issues

[synaesthesia]

Unfortunately as it's dead I can't see that, but I'm inclined to suspect you might be right about the battery - exported the event logs and seeing time drifts of around half an hour every couple of hours.

Cheers

[synaesthesia]

Bum, nope not that. Battery is fine but still thinking along those lines perhaps - damaged BIOS maybe. Been flashed to latest version already.

Investigation continues!

[Fazza]

Have you tried resetting the CMOS via the motherboard?  You usually have to short out a couple of pins on the motherboard and then give it a go - depending on the generation of the desktop it may even be an actual button you can press!

Edited May 21 by Fazza

[synaesthesia]

24 minutes ago, Fazza said:

Have you tried resetting the CMOS via the motherboard?  You usually have to short out a couple of pins on the motherboard and then give it a go - depending on the generation of the desktop it may even be an actual button you can press!

Yeah, done the whole shebang there including shorting the battery connectors while hitting power button (power disconnected) for 30 seconds to clear.

Currently attempting to flash it - I said I had done that but I was clearly thinking of another machine, it's refusing to do so.

I might be tempted to desolder & replace the BIOS chip as I have a dead motherboard for one of these

[Fazza]

15 minutes ago, synaesthesia said:

I might be tempted to desolder & replace the BIOS chip as I have a dead motherboard for one of these

 

That's the old-fashioned way of doing it!

 

What you want is one of these:

 

 

It's a CH341A Programmer and you just hook it up to your computer, connector the other end over the CMOS chip where the BIOS is stored, save it to a ROM file and then flash/write it to your computer with the issue!  You can even download the ROM from the manufacturers website and flash that directly to the chip on the motherboard.

 

😎

Edited May 21 by Fazza

[synaesthesia]

I sh** you not, I have one winging it's way to me from China as I type this

Not for work specifically but it's being delivered here (hopefully) so you never know!

 

[Fazza]

3 minutes ago, synaesthesia said:

I sh** you not, I have one winging it's way to me from China as I type this

Not for work specifically but it's being delivered here (hopefully) so you never know!

 

 

I have one at home and at work, there is a hardware bug on them though so be sure to check it out before plugging it in to your PC, I had to modify mine by desoldering a pin and then soldering in a wire to the correct voltage if I remember correctly, something about 3V and 5V getting mixed up I think..

[synaesthesia]

Ooh cheers, will do; I know the stuff from AliExpress tends to come sans-documentation (or as good as) so good to know!

[Fazza]

2 minutes ago, synaesthesia said:

Ooh cheers, will do; I know the stuff from AliExpress tends to come sans-documentation (or as good as) so good to know!

 

This is the video I used to modify mine:

 

 

[synaesthesia]

Oooh think I remember that one. Adamant and Sorin from electronicsrepairschool make up much of my Sunday viewing when I'm fishing (and clearly not catching!)

[Fazza]

24 minutes ago, synaesthesia said:

Oooh think I remember that one. Adamant and Sorin from electronicsrepairschool make up much of my Sunday viewing when I'm fishing (and clearly not catching!)

 

Do you have a coffee with Sorin on Sunday mornings?!

[synaesthesia]

It's usually about midday when I get to these, when the lack of catching kicks in and I need something to keep my mind active and keep up the pretence of patience

But yes, there's always coffee involved!

[chazzy2501]

when you diagnosed the PC in the office did you also use the original keyboard and mouse? Funky peripherals can do odd things.

[Fazza]

22 hours ago, chazzy2501 said:

when you diagnosed the PC in the office did you also use the original keyboard and mouse? Funky peripherals can do odd things.

 

True, I have a USB keyboard in the cupboard that randomly types random letters as soon as you plug it in!  Always worthwhile changing over the keyboard and mouse on systems with strange problems.

[synaesthesia]

Hah, nope - my own tried & tested kit in office. So far though, *touches wood* the PC Poltergeist doesn't appear to have struck since it got put back...

 

[MrEprise]

I've had HP desktops do strange things like this before. In my last place had a dc7700 which after shutting it down (or forcibly turning it off) would just turn itself back on again. Where I needed a temporary makeshift server for something, I used this PC as we couldn't really use it anywhere else and it meant it couldn't be accidently turned off in any way where it couldn't be easily restarted.

I guessed this probably had a bad flash of the BIOS or AMT firmware at some point.