Question / Help OBS causing BSOD and crashes

G

Gepsu

New Member
Hey

Since I updated OBS to the latest version (20.1.1), it has been doing this. Version 20.0.0 still works flawlessly. Whenever I click the record or stream button, 1/10 times it works fine, 6/10 times it gives me BSOD, 3/10 times it just crashes. I've been trying to figure this out for a while and I just can't so I thought i'd ask here if anyone can help. I included the crash log.

Thank you in advance and let me know if there's anything I can do to help.

Update:
- BIOS updated, no more BSOD, only crashing
- Added more recent crash log
- Found a solution

This works:
sam686 said:
Try custom x264 option:
asm=AVX2 to turn off AVX512.
or, asm=SSE4.2 to turn off all AVX.

Note that trying to use asm=AVX512 on a CPU that don't support it is an instant crash.
My CPU don't support AVX2 either (i7-2600) that using asm=AVX2 also result in an instant crash to my CPU.
https://github.com/mirror/x264/blob/master/common/cpu.c

If custom x264 option asm=AVX2 works as turning off AVX512, no need to have separate builds.
Click to expand...
 

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Last edited:
D

Dilaz

Member
Crashes in libx264 are caused either by unstable overclock or hardware issues. If you have overclocked your cpu, remove that and try again.

User level applications like OBS can't cause BSOD, only trigger them. BSOD can be caused by driver or hardware issues.
 
G

Gepsu

New Member
Dilaz said:
Crashes in libx264 are caused either by unstable overclock or hardware issues. If you have overclocked your cpu, remove that and try again.

User level applications like OBS can't cause BSOD, only trigger them. BSOD can be caused by driver or hardware issues.
Click to expand...

Thank you for your reply. I tried again and everything works perfectly in 20.0.0, but the same issue still occurs in the latest version. I must've derped or something when trying out different versions... My bad. Drivers are up to date and i haven't overclocked this.

Did they change something that might cause this? Is there anything else I could try? And if it's a hardware issue, how do I know what is causing it?
 
Last edited:
D

Dilaz

Member
x264 was probably updated to support AVX-512 on your CPU. That is a new feature in Intel CPUs that most softwares are not using.

You could try to update the BIOS on your motherboard
 
R

R1CH

Forum Admin
Developer
Most AVX-512 supporting motherboards are currently broken as they run the clock too high to support stable operation. Check you have the latest BIOS and/or set a large AVX offset in your BIOS.
 
G

Gepsu

New Member
sam686 said:
TurboBoost (with specific motherboard settings) + AVX-512 on i7-7820X is what might be making things unstable.

Either: turn off TurboBoost, or use negitive AVX offset, or look for BIOS/Motherboard update with reset motherboard settings.

This has happened to others.
https://obsproject.com/forum/threads/x299-turbo-boost-bug-obs-crash-bsod-workaround-inside.76449/
https://www.google.com/search?q=turbo+boost+7820x+fix
Click to expand...

I found that post a while after I posted mine. I wasn't sure what I was looking for before. More below...

R1CH said:
Most AVX-512 supporting motherboards are currently broken as they run the clock too high to support stable operation. Check you have the latest BIOS and/or set a large AVX offset in your BIOS.
Click to expand...

After I updated BIOS it only appeared to crash and not trigger BSOD. Disabling TurboBoost didn't make a difference. And I also looked into AVX, saw a list of negative numbers, but I wasn't sure what it was as I've never heard of it till today, so I just let it be. I don't feel very comfortable touching settings that I dont know what they are.

Is this a pc specific problem or is this something that can/will be fixed in obs? Should I just stick to 20.0.0?
 
R

R1CH

Forum Admin
Developer
This is a platform specific problem with any CPU that supports AVX512 (a high speed instruction set on newer Intel CPUs). The latest version of OBS uses a version of the x264 encoder that uses AVX512 instructions, as that should result in faster performance. However many of the desktop platforms that support these new CPUs were rushed out without proper testing, and actually trying to use AVX512 on them results in crashing. You don't see this with other apps or older versions of OBS because the newest x264 is one of the few applications that tries to use AVX512.

The fault lies with the motherboard manufacturers and/or Intel, OBS and x264 developers are doing everything correct, but the vast majority of AVX512 desktop CPUs seem incapable of actually running AVX512.

We're considering building a new version of x264 with the AVX512 optimizations removed, but this would also be unfair to those people who have no problem using AVX512 (eg Xeon CPUs with better platform support). For now we can only hope that motherboard manufacturers continue to release updates to make AVX512 stable on their platforms.
 
S

sam686

Member
Try custom x264 option:
asm=AVX2 to turn off AVX512.
or, asm=SSE4.2 to turn off all AVX.

Note that trying to use asm=AVX512 on a CPU that don't support it is an instant crash.
My CPU don't support AVX2 either (i7-2600) that using asm=AVX2 also result in an instant crash to my CPU.
https://github.com/mirror/x264/blob/master/common/cpu.c

R1CH said:
We're considering building a new version of x264 with the AVX512 optimizations removed, but this would also be unfair ...
Click to expand...
If custom x264 option asm=AVX2 works as turning off AVX512, no need to have separate builds.
 
G

Gepsu

New Member
sam686 said:
Try custom x264 option:
asm=AVX2 to turn off AVX512.
or, asm=SSE4.2 to turn off all AVX.

Note that trying to use asm=AVX512 on a CPU that don't support it is an instant crash.
My CPU don't support AVX2 either (i7-2600) that using asm=AVX2 also result in an instant crash to my CPU.
https://github.com/mirror/x264/blob/master/common/cpu.c

If custom x264 option asm=AVX2 works as turning off AVX512, no need to have separate builds.
Click to expand...

'asm=AVX2' works! Thank you very much :)
 
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