You mean with "is solved" probably "will get solved", right? So yes, here we go.

I really didn't want to remove the PSU. I don't have any spare ones lying around and the server is hosting about 10 Internet sites and serving as a domain controller, so any downtime is bad. Also it's almost running permanently, so shutting it down is a minor issue. But as I want this fixed, I took the effort to take it apart again.

As I don't have spare PSUs (only old ones) I took apart my working client machine, which had the PSU Enermax MODU87+ 900W. It took me a few hours to take it out (connector is under the CPU cooler) and that stuff, but anyway, I tried. Same problem there. So the PSU is not the reason for this shutdown problem, although I hoped it was, because I don't like that Flower PSU (it had some mechanical issues).

All hardware I use: almost nothing, this is a server. Here's the complete list:

• Memory 32GB (4x8GB Kingston HyperX DDR3-1600 CL9 1.5V)
  
• CPU Intel Core i7 3770K BOX, 3.5GHz, LGA1155, 4C/8T, unlocked, with included original cooler (BX80637I73770K)
  
• case is a Compucase S4UT6, 19", 4U/Tower server rack, which includes some ventilators and stuff
  

externally connected:

• Power
  
• HDMI cable
  
• RJ45 network
  
• keyboard+mouse (both PS/2) via KVM (LevelOne KVM-0410) to a Sharkoon USB to PS/2 converter
  

No other USB devices. Any further ideas?

So you're saying the system tries to boot, but can't, probably because it's being shut down? Remember that Restart works without problems.

I don't have such a diagnostic card and the link you point me to shows a PCI card, but the Sabertooth Z77 has no PCI slots, only PCIe. No, the Sabertooth Z77 doesn't have a q-code display (my main client computer has it; it's a ROG). I might order such a diagnostic card, but it might take weeks and I didn't find any PCIe ones yet (only Mini PCIe for Notebooks). Let me know if you find a link and you still think I need it to debug. The Sabertooth Z77 has LED indicators that show where the problem is. If the RAM has a problem, then the RAM LED lights up, etc. Please have a look at the manual, chapter 2.2.7, page 2-16 in the English version.

I looked at the LEDs and there was no difference when shutting down. All lights were off (DRAM, CPU, BOOT_DEVICE, VGA), only the main one was in this greenish yellow (didn't change color when shutting down) indicating all "no problem". After cutting the power, some do quickly light up and also some light up quickly during POS before turning off.

I agree it's not a very important problem, especially for a server that should run permanently. I don't want to turn it off all the time. But I do want it fixed. Why? For these three reasons:

• This is a new build and I do want that everything works. If I have to exchange it in three years, because I want to use it as desktop computer then, the warranty is over.
  
• If this is broken, what else? Maybe there are more hidden problems.
  
• My last server that this replaces ran for many years without issues. It was a Pentium 4 based machine, so very old. Suddenly, after 2-3 days, I got a black screen. I thought of APT and stuff (it's running a webserver) but couldn't find anything. So I replaced it with an identical machine I had lying around and threw away the old one. Suddenly this replacement machine had the same symptoms. Black screen after 2-3 days running. So it can't be that this replacement machine has the same hardware problem without malware (I only took over the harddisks). But I think the reason was that the webserver was just getting increased traffic causing more CPU power and the CPU had only a small passive cooler so it turned off due to overheat. The moment I found that out it was too late, I assume the CPU died, so I had to throw it away too any buy this new setup. I'm afraid that I get black screens again and do not know where they come from - just a power outage, a boot after reinstall, etc. Turning it off should simply work.
  

So essentially you're saying you can't help any further. Did I understand this correctly?

Motherboarder wrote:
So you're saying the system tries to boot, but can't, probably because it's being shut down? Remember that Restart works without problems. I am trying to find out why and what is going on, while not being near the system myself. It is pretty difficult to do any kind of diagnostics from a distance but we try. And what I described is a possible cause. The flashing cursor that is what is the curve ball here.

I don't have such a diagnostic card and the link you point me to shows a PCI card, but the Sabertooth Z77 has no PCI slots, only PCIe. No, the Sabertooth Z77 doesn't have a q-code display (my main client computer has it; it's a ROG). Any diagnostic card, PCI or PCIe will work on that board my friend you simply put it in the PCIe slot and it works. Amazon or ebay will have one that can ship to Switzerland. Not difficult to search for one online honest. 🙂

So essentially you're saying you can't help any further. Did I understand this correctly?

And finally no you have not understood me correctly. I am not one to give up easily and nor are you I am sure.

If as you suggest there is no problem with the hardware, the LED lights then the problem has to be else where yes. And what is left? Software and OS. What are you doing to ensure that your server software and OS are not the contributing factors to this? I am asking to try and fill in some blanks and maybe that way find out what causes this and therefore how to fix this issue.

I would still get the diagnostic card, it is a very handy tool for anyone who builds systems. Not all board have the built in poster. Use the following search terms in Amazon "motherboard diagnostic tool"