XMP-profile or any kind of overclocking makes screen flicker with G.Skill F4-3600C16D-32GTZNC and AM4 B550 Phantom (solved)

Algar

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Nov 27, 2021
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I can't seem to bring G.Skill F4-3600C16D-32GTZNC memory past the default 2133mhz. Already modest overclock to 2400mhz results in random flickering and artifacts (black and white lines appear randomly here and there).
Mobo is: ASrock B550 Phantom Gaming ITX/ax
Processor: AMD Ryzen 7 5700G APU (I'm using integrated graphics).
Power: HDPLEX 400W NanoATX
Operating system: ArchLinux, Fedora, Garuda etc.
Resolution: 4k

The system seems to run most cool with XMP & 3600mhz timing (unless of course I use the default 2133mhz settings). I've set up infinite fabric to auto or 1800mhz but it doesn't seem to make a difference for the flickering. Also setting the DRAM Voltage to auto or 1.350 doesn't seem to make a difference for the flickering.

Undervolting the APU very slightly or setting up a negative curve in PBO doesn't seem to make a difference. My temperatures aren't perfect (processor around 55-65 degrees and m/b around 35-40 degrees) and my airflow is currently limited but I guess temps are in OK range?

The timings that the XMP suggests are 19-19-19-19-39
Without XMP, on 2133mhz, bios defaults them as 15-15-15-15-36, which works also fine (without flickering/distortion) on 2133mhz.

What could I try next?

edit: clearing mobo's CMOS with a jumper seemed to clear the problem
 
Last edited:

Dan_D

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I've never heard of RAM settings causing a flickering display.
 

Algar

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Can you screenshot the artifacts?
And run a memtest program to check the RAM for stability.
I would suggest TM5 and load the Extreme1@anta777 config.
If you get errors in the test try one stick at a time to see if one is doa.

I discovered that the screen works correctly with only one memory. When in dual channel the flickering begins. Both of the memory cards work fine in single channel. Also motherboard's card slot 1 works as well as card slot 2, in single channel. When I load both, the flickering starts.

It's hard for me to take screen shot. The artifacts blink so randomly and quick. They are either black or white vertical lines. The flickering lines don't quite go all-the-way from side to side but they are quite long.

I'll be trying that memtest later. I'll need to run windows from an usb stick, which is a hassle...
 

pendragon1

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try bumping the ram voltage to 1.4v(its safe), timings to 20-19-19-19-39 and vsoc/vdrsoc/vddsoc(whatever its called) to 1.1v
 

Kardonxt

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Apr 13, 2009
Messages
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You may want to make sure you mobo BIOS is fully up to date if you haven't already.

As for memtest I would run memtest86 from a bootable flash drive and not worry about messing with Windows. https://www.memtest86.com/ ( Test with XMP enabled since the ram seems to work fine at JEDEC settings. )

EDIT: I just noticed you posted that the flickering stops when in single channel. Just to be clear that's at XMP settings?
 
Last edited:

TheSlySyl

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Are you using a dedicated GPU or the APU?

Cause if you're using the APU for graphics output, that kinda makes sense because it uses system ram.
 

TheSlySyl

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2,278
Somehow that line completely passed me by when looking at the specs.

I would boost the ram voltage and loosen timings, as has already been stated. Also, ridiculous as it sounds, maybe give a new cable a try? That's solved more issues for me with video output than i'd ever expected.
 

dasa

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Messages
606
Since both sticks work ok on there own I would defiantly be looking at the BIOS and increasing the V as suggested above.

Memtest is not very good at detecting memory controller instability unfortunately which is what is more likely the problem when both sticks work on there own but not together but still worth a go since you don't have windows.
 

Algar

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try bumping the ram voltage to 1.4v(its safe), timings to 20-19-19-19-39 and vsoc/vdrsoc/vddsoc(whatever its called) to 1.1v
Doesn't seem to help. Might be that the flickering is reduced but maybe I'm just imagining things.

You may want to make sure you mobo BIOS is fully up to date if you haven't already.

As for memtest I would run memtest86 from a bootable flash drive and not worry about messing with Windows. https://www.memtest86.com/ ( Test with XMP enabled since the ram seems to work fine at JEDEC settings. )

EDIT: I just noticed you posted that the flickering stops when in single channel. Just to be clear that's at XMP settings?

The BIOS is fully updated. Yes, that's XMP-settings @ 3600mhz. XMP runs perfect with single channel and the screen is completely clear.
So I seem to have a problem running memory in dual-channel. Also I can't find in the BIOS any statement that I'm actually running the memory in dual channel configuration.
I'll try next if there is something wrong with my m/b with a different set of memory. I'll manage to run the memtest86 and find a different cable later...
 

Algar

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The screen went totally bonkers when I tried default XMP setting with Crosair Dominator 2x4gb memory. All the voltage and timing settings were defaulted prior to testing. Screen was full of artifacts and the whole computer collapsed after a few minutes. XMP settings look now fine with only one Dominator memory module. But it seems like my operating system is now broken.
 

Algar

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How can I check if my memory works in dual channel in memtest? In memtest86+ it looks really easy to find out:

..but I can't get memtest86+ to run at my setup.
 

Kardonxt

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With matching sticks and board with only 2 slots, it's pretty safe to assume the ram is running in dual channel. Unfortunately Memtest86+ hasn't been updated since 2013 or something silly like that.

Do you get artifacts in BIOS? If BIOS looks OK, you may want to try a Windows install just to rule out any weird Linux compatibility issues.
 

Algar

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The memory is working in dual-channel. I managed to check it.
No artifacts in BIOS.
This time I installed Windows 10. The same problem (flickering lines while the memory is clocked over 2133mhz) started to appear in Windows 10 only after I installed AMD's display driver... It might have something to do with 4k resolution... I'll try to use HD-resolution when I get home...
 

dasa

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606
Can you show us what settings the MB is using with Zentimings when you enable XMP. Then we may be able to suggest some custom tweaks to improve stability.
Although it would help if you had a stress test like memtest or tm5 which was showing consistent errors that we could target.
 

Algar

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I noticed that lower than 4k resolutions didn't result in flickering lines with XMP. That's probably why there weren't any artifacts in BIOS (it's in HD-resolution). And that's why the errors started to appear after installing display drivers (before that the resolution was lower than 4k). Increasing and tweaking the voltages didn't help.
However I've been quite stupid for ignoring the obvious. I. e. clearing the CMOS with a jumper cleared the problem. XMP works now as supposed. Probably some strange bug. Bluetooth was also acting strange but now it's working correctly. I somehow thought that when updating the BIOS would have resulted in clearing the CMOS. Anyways I hope things will keep up and the problem won't come back.
Thanks for the help! I'll still run memtest in case....
 

learners permit

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Great news as I am considering a very similar system for a htpc build because graphics card pricing is ignorant right now
 

Algar

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Great news as I am considering a very similar system for a htpc build because graphics card pricing is ignorant right now
I'm very happy with this setup now. The sound quality with the ASrock B550 Phantom Gaming ITX/ax is great (much better than with my old laptop), image is clear and games run nicely. Power consumption/heat generated is low. Starts in an instant with an NVMe (faster than my stupid smart-TV).
 

wzis

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I can't seem to bring G.Skill F4-3600C16D-32GTZNC memory past the default 2133mhz. Already modest overclock to 2400mhz results in random flickering and artifacts (black and white lines appear randomly here and there).
Mobo is: ASrock B550 Phantom Gaming ITX/ax
Processor: AMD Ryzen 7 5700G APU (I'm using integrated graphics).
Power: HDPLEX 400W NanoATX
Operating system: ArchLinux, Fedora, Garuda etc.
Resolution: 4k

The system seems to run most cool with XMP & 3600mhz timing (unless of course I use the default 2133mhz settings). I've set up infinite fabric to auto or 1800mhz but it doesn't seem to make a difference for the flickering. Also setting the DRAM Voltage to auto or 1.350 doesn't seem to make a difference for the flickering.

Undervolting the APU very slightly or setting up a negative curve in PBO doesn't seem to make a difference. My temperatures aren't perfect (processor around 55-65 degrees and m/b around 35-40 degrees) and my airflow is currently limited but I guess temps are in OK range?

The timings that the XMP suggests are 19-19-19-19-39
Without XMP, on 2133mhz, bios defaults them as 15-15-15-15-36, which works also fine (without flickering/distortion) on 2133mhz.

What could I try next?

edit: clearing mobo's CMOS with a jumper seemed to clear the problem
I have the similar issue: in BIOS, it shows as 2133Mhz, but in my case, in the setting of memory page in BIOS (my mob is ASUS Tuf Gaming B550M Plus WIFI), I can set it to 3600Mhz and boot the machine up. But just don't understand why the BIOS only detected it as a 2133Mhz ones.
 

learners permit

[H]ard|Gawd
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That's what the jedec specification is for those memory chips. Download and install cpu-z and click the spd tab to see all spd info for your memory modules.
 

kirbyrj

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Feb 1, 2005
Messages
30,107
I have the similar issue: in BIOS, it shows as 2133Mhz, but in my case, in the setting of memory page in BIOS (my mob is ASUS Tuf Gaming B550M Plus WIFI), I can set it to 3600Mhz and boot the machine up. But just don't understand why the BIOS only detected it as a 2133Mhz ones.

That's in place to ensure it will boot properly under the widest range of hardware. 3600Mhz memory wouldn't work at the rated timings/speeds with an older AMD CPU for example, but would work fine at 2133 up to 2933 or so.
 
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