This is a weird one, so I'm just looking for opinions on where to start narrowing it down.
I recently was given a couple of old HP Z600 workstations, pretty capable beasts despite their age and limitations. Supplied originally with Windows 7 Pro.
Both have been updated (by me) to SSDs and dual CPUs, one now with faster Xeon X5675 (3.06GHz) chips. Old Nvidia GeForce GT730 video cards in both.
They only have TPM1.2 and are not upgradeable to TPM2.0 but both are running Windows 11 Pro generally well.
The slower one (2*X5660 @ 2.8GHz) is currently little-used but has exhibited no issues whatsoever.
The faster one is used daily and so far has had one "blue screen", a System Thread Exception in nvlddmkm.sys which is part of the Nvidia driver. I'm not too fussed about that as I'll probably upgrade the video card soon and I've only seen it once.
The weird problem is that sometimes it doesn't boot, but just hangs. Maybe 1 in 10, 1 in 20 or less, I've only just started logging occurrences.
Specifically it goes through all the BIOS stuff, goes to boot from the "Hard disk" (SSD) and the four blue squares of the Windows logo appear and that's it - it will stay like that for hours if left. Nothing seems to interrupt it other than pressing the power button. Wait a few seconds, power back on, it's fine.
Normally, once that logo appears, it's about 2 seconds before the "whirling dots" appear below it and off we go and the desktop soon appears.
Searching online doesn't bring up much useful other that suggesting what I do (power cycle) or restarting via safe mode, but there's a common implication that it's possibly video card related. This system does have 3 monitors connected which may or may not be relevant, the "slower" unit only has one.
The only change I've made recently is to increase the POST delay from 5 seconds to 10 and the frequency of hangs "seems" to have reduced, but realistically it's not been long enough to be at all certain.
Any thoughts anyone? e.g. power supply, video card, something else?
