## New Case-Fan Installed

During previous postings, I had written about crashes, which the computer I name ‘Phoenix’ was suffering from. And I had written that one possible reason could have been the failed case-fan, which could have been causing something on the motherboard to overheat.

Just today, this box suffered from another similar crash. This time, I opened up the case, and replaced the 92mm case-fan. Therefore, the reader might expect some optimism on my part, that this server-box will not crash again. But in reality I have two reasons, for which my optimism does not overwhelm:

1. If an overheated chip has already caused crashes, there is some tendency for it to suffer from a memory-effect, of wanting to fail again, whenever it gets slightly warm, or just so. Therefore, due to the first crash possibly having happened for that reason, this machine could now have a penchant for crashing, even though the initial cause has been removed.
2. The cause may not have been an overheated chip, but rather, a pure software-problem with the legacy graphics driver (nVidia). On such a big display, the graphics driver may have been suffering from some sort of resource leak – aka memory leak – and during boot-up, the BIOS displays it only possesses 128MB of shared RAM! Thus, the problem could be cumulative and result from regular copying-and-pasting, with many HW-accelerated drawing surfaces and many compositing effects enabled. Once we have an unstable graphics driver – and the graphics driver has received several updates recently – having a stable one could be a luxury we cannot easily reproduce.

I was down from roughly 19h00 until 20h00, and apologize to my readers for any inconvenience.

Dirk

BTW: I have an additional reason, not really to believe, that these crashes are due to an overheated graphics chip. During the actual reboot, the graphics chip should get especially hot, and especially so, if the case-fan is not turning.

I can see that if this chip did overheat, the TDR would not be able to reboot it.

But the crashes never seem to occur, directly after the reboot. I generally seem to obtain about 6 days of smooth computing, before another crash happens.

Also, it should not be a VRAM leak, because this is a pre-GPU-type graphics chip. With the old graphics chips, that maximally had several pixel and several vertex pipelines, VRAM consumption was more or less static, while with the more-modern GPUs, some amount of VRAM-creep is at least plausible.


root@Phoenix:/home/dirk# lspci | grep vga
root@Phoenix:/home/dirk# lspci | grep VGA
00:0d.0 VGA compatible controller: NVIDIA Corporation C61 [GeForce 6150SE nForce 430] (rev a2)
root@Phoenix:/home/dirk# lspci -v -s 00:0d.0
00:0d.0 VGA compatible controller: NVIDIA Corporation C61 [GeForce 6150SE nForce 430] (rev a2) (prog-if 00 [VGA controller])
Subsystem: Hewlett-Packard Company Device 2a61
Flags: bus master, 66MHz, fast devsel, latency 0, IRQ 21
Memory at fb000000 (32-bit, non-prefetchable) [size=16M]
Memory at e0000000 (64-bit, prefetchable) [size=256M]
Memory at fc000000 (64-bit, non-prefetchable) [size=16M]
[virtual] Expansion ROM at f4000000 [disabled] [size=128K]
Capabilities: [48] Power Management version 2
Capabilities: [50] MSI: Enable- Count=1/1 Maskable- 64bit+
Kernel driver in use: nvidia

root@Phoenix:/home/dirk#




## Another possible hypothesis, for why my server-box sometimes crashes.

I have written before, that my Linux computer ‘Phoenix’, which acts both as my server and a workstation, sometimes crashes. I have another possible explanation for why.

The graphics chip on this machine is only a , capable of OpenGL 2.1.2 using proprietary (legacy) drivers. It only has 128MB of shared memory with my motherboard.

Under Windows 10, this chipset is no longer supported at all.

I may simply be pushing this old GPU too hard.

My display is a 1600×1200 monitor, and much of the graphics memory is simply being taken up by that fact. Also, I have many forms of desktop compositing switched on. And at the time of the last crash, I had numerous applications open at the same time, which use hardware 2D acceleration as part of their canvas. And I was copying and pasting between them.

I am hoping that this is easing the burden on my equally-dated CPU.

But then the triggering factor may simply be an eventual error in the GPU.

The fact that the Timeout Detection and Recovery (‘TDR’) does not kick in to save the session, may be due to the possibility that the TDR only works, in specific situations, such as OpenGL, 3D rendering windows. If the GPU crash happens as part of the compositing, it may take out the X-server, and therefore my whole system.

The only workaround I may have, is to avoid using this box as a workstation. When I avoid doing that, it has been known to run for 60 days straight, without crashing…

Dirk

(Edit 01/28/2017 : )

I use a widget on my desktops, which is named ‘‘, and I find that it gives me a good intuitive grasp of what is happening on my Linux computers.

This widget has as a disadvantage, that when extensions have been installed to display temperatures, sometimes we do not know which temperature-sensors stand for which temperature. This is due to the fact that Linux developers have to design their software, without any knowledge of the specific hardware it is going to run on. Inversely, the makers of proprietary drivers know exactly which machine those are going to run on, and can therefore identify what each of them stands for.

This also means, sometimes we have temperature readings in ‘‘, which may just be spurious, and which may just constantly display one meaningless number, in which case we reduce our selection of indicated temperatures to ones we can identify.

In the context of answering my own question, another detail which becomes relevant, is the fact that this tower computer has a failed case-fan, which is accurately being indicated as the ‘‘ entry, running at 46 RPM at the moment of the screen-shot. I know that this case-fan is in fact stalled, from past occasions when I opened up the tower.

## Plausible does not mean Assumed

I could make hypothetical guesses, as to why crashes like this one happen, on the machine I name ‘Phoenix’, which was manufactured in 2008. This time I noticed, that the cursor on the screen stopped moving, then that mouse-input was not being interpreted, then that the screen just filled with an image, which was a diagonally-scrambled version of the normal screen content:

• It could be that the old GPU is no longer reliable at the hardware level, and that it may now suffer from random crashes, which also crash the X-server. The “” (‘‘) feature I have seen the nVidia Driver execute properly in past situations, may just not kick in.
• When I reinstalled, replacing the old 32-bit O/S with the current 64-bit O/S, I also replaced the 2GB of RAM with completely new, 4GB of RAM, and the “” (‘‘) of the new RAM has also become faster, that becoming 800MHz instead of the earlier 600MHz. Either set of DDR RAM modules was running with dual-channel capability. The motherboard may detect this capability of the new RAM modules and start using it, as the motherboard itself may have the stated capability of running at 800MHz. Yet, at 800MHz, the way this Motherboard works may not be stable.
• There could be some sort of kernel issue…

What I do find a bit more specific, is the fact that there seem to be no log entries for the , suggesting that although an X-server crash eventually takes place, this may not be the root cause. Also, the fact that the mouse has become unresponsive for a few seconds, before screen-content collapses, seems to suggest the same thing…

But the most important fact for me to observe, is that simply being able to suggest plausible reasons for the crash, is not the same thing as having diagnosed the crashes. Honestly, I do not know at present, why this type of crash happens.

One of the observations about this machine which had impressed me in the past, was that I had pushed 3D rendering beyond the limits of the old GPU, thereby crashing this graphics chip, but that the desktop manager I had in place was able to restart the GPU, and to resume the session, without requiring any action from me, but displaying a well-behaved message to the effect that the GPU needed to be rebooted. This is called “” (‘‘), and does the same thing under Linux, that it does under Windows, and depends on stable graphics drivers.

The fact that I do possess ‘‘ on this machine suggests, that a simple failure of the graphics chip, should not take out my session.