Problem: The system does not boot, the power button is red or it start doing bips, and the boot process does not even start showing usual messages on the display.


Solution:


This is a hardware issue, but not necessarily a broken component.


First thing analyse what was done to the system, if it was moved or serviced in any way then it is obvious that something went wrong


Disconnect the power cable and press the power button 6 seconds, until it does not light or bip any more. Then try again.


If there are is a sound like "bips", check the bip codes in the manual of your workstation or google for it. Each number of bips indicate a different issue.


Bypass any UPS that could be in the electrical path and use a reliable power plug. Most UPS degrade over the time and there is a point that they can not support the initial power peaks. Also make a test with all the monitors and all devices are connected to the same power stripe as the workstation. Earth level differences and other electrical issues are one of  the most  common causes for a problem like this.


If you don't know the hardware component that is failing then remove all the cables, all internal boards, internal hard disks, the power supply, and all the external devices and USB peripherals. Then reinstall only the necessary item for basic diagnostics: Just the Power supply, RAM memory, a  GPU and the monitors. If it works in this basic setup then start adding the other components one by one. If it does not work replace the GPU (any simple GPU can work for diagnostics). If still does not work contact HP support.



Problem: The system was working fine but now it does not boot and it says "there is no operating system"


Solution:


Remove all external disks and pen-drives and try again, in some systems they could make a mess around with the boot sequence.


If it does not work then please contact support, as there could be a serious problem with the system disk. Please try to describe how it happened and what other changes were made before the last boot.


If possible, connect the system disk to other system (as a secondary drive) just to check that it still works (do not make modifications if you are not sure).


Problem: The system was working fine but now it does not boot, it start booting but then it stop  and it says "the filesystem needs to be checked manually" or similar message,


Solution:


From time to time  the OS  check the boot disks (also after a system crashs or blackout) . Some errors are considered dangerous to fix and require user to confirm. Typically by using the fsck program. But this can be a bit delicate so please contact support if you are not sure about what happened. Also make a picture of the exact messages on the screen and send it to support.


Problem: The system start booting but it goes into text mode, there is no graphics login  ( it can not start X)


Solution:


Check  that we are not in any of the previous cases (that you do not see the previous error messages).


You will need to login in text mode as root,   But If it does not even offer a login prompt, then you can force the system to boot in text single user mode as follows:


 Power off / Power on the system, and when you see the initial linux grub menu:


 - Suse11 systems:  In the boot options, just add this word at the end:  single and press Enter


 - CentOS systems:  Press e to edit the options. Then you will need to scroll down with cursor keys until you find the line starting with "Linux16...". (this line is not visible until you scroll down)   Then  use right cursor arrow to move the cursor to the end of that line (this options line is typically longer that the terminal capabilities, so just keep using right cursor arrow until it does not advance anymore) and add the word single at the end.   Then do not press Enter, after adding the word  single just press Ctrl + X


That will boot in single mode, offering a text login prompt. 


Login as root (type the root password and press Enter) and execute these commands:


mv /etc/X11/xorg.conf  /etc/X11/xorg.conf.backup

nvidia-xconfig

reboot


This will recreate the proper settings for your current GPU and monitor setup.


If it does not work:


If there are monitor  extenders it can be a problem with them.  Disconnect the extenders , connect at least one monitor directly and restart the system. This will confirm or discard if it is a problem with the extenders or not.


Another cause for this may happen when installing a new graphics board, as they may require a new driver.  This is explained here:


http://support.sgo.es/support/solutions/articles/1000240826-how-to-install-nvidia-driver-on-linux 


Even if you installed a new  driver for it it could be lost on next reboot (some old drivers were installed directly in the boot image and reappear on next reboot).  The solution  is explained  at the end of the document):


(You can contact support if you need help with it. Meanwhile you could reinstall the driver for another session, but in a case like this it will lost again on next reboot)


If it was not that,   if the problem happened just after the system was moved or serviced check that the graphics board is still firmly attached and also the internal power cable that goes to the graphics board. Also remove every other board or internal devices that are not required to boot the system and try again.


Check that the system disk is not full (login in text mode and execute the df command). If it is full please check the next point:


Bypass any UPS that could be in the electrical path and use a reliable power plug. Most UPS degrade over the time and there is a point that they can not support the initial power peaks. Also make a test with all the monitors and all devices are connected to the same power stripe as the workstation. Earth level differences and other electrical issues are a  common causes for a problem like this.



Problem: The system boots but it does not permit to login (the graphics login screen is there, but it does not let you login)


Solution:


The most common cause is a system disk full or /home partition full. It can happen due to not obvious reasons, like a render or copy process going to the wrong place by mistake, or a a software component going out of control and creating too many logs, big temporal files due to using drag & drop for copying big files, etc. So first thing is to try this:


Login in text mode and execute this command:


df


It will tell you Disk Free for each partition. Check that none of the important partitions are full (mainly  "/" and "/home" ).  If it is full, execute this to make some space:


rm -rf /tmp/*  /usr/tmp/* /home/mistika/InstalledMistikaUpgrades/*


That will give you some extra space.  Then boot again and try to find where you have big files that caused the system disk to fill up and to prevent it to happen again.



Problem: The system boots, but only one of the two GUI monitors is working


Solution:


Check the monitor extenders. They are the most common cause for a problem like this.