HDMI signal problem with Ryzen Pro 4750G

[A Computer Guy]

Whenever I run Cinebench R15, R20, or R23 the HDMI video signal becomes unstable and lost only over HDMI. After the cinebench run the video signal recovers and displays the screen properly.
(Currently running Windows 10.)

Interestingly this doesn't happen over the DisplayPort connection. In RDP sessions this still occurs to the connected HDMI monitor however the RDP session itself is still fine. In some cases the screen will display noise instead of a complete signal loss and it takes awhile for the system to recover the signal.

I've tried several HDMI cables and different resolutions from 1080p up to 4K with the same results.
I'm about ready to pull the CPU and try it in another board but before I do perhaps someone might be familiar with this kind of issue and give me some pointers in troubleshooting it.

Obviously I got this CPU aftermarket pulled from an OEM system so there is a chance something might have been wrong with it. My other thought is perhaps my HDMI port is bad.
I can run the Final Fantasy xiv Endwalker benchmark no problem so it might not be strictly a graphics related issue.

This is my first Pro APU and something I noticed is MCLK, FLCK, and UCLK along with SOC voltage seems to fluctuate unlike my other non-g ryzen CPU's.
Typically under CPU load it will ramp up to DDR4-3200 frequency under load and SOC voltages will spike up a bit.

Also interesting is when the PC is idle EDC always hovers around 60% which doesn't seem normal to me but I don't have a similar APU to compare against.

 

[tabascosauz]

A variance of 0.02V for VSOC is nothing. Use HWInfo to monitor.

APUs have strong SOC but your VSOC is low especially for iGPU use. An active iGPU automatically increases VSOC requirements at all times even if all other settings remain the same, because VDDCR_GFX derives from VSOC and iGPU draws power from SOC plane.

My 4650G does the same blacking out on HDMI when Vega 7 is not happy with VSOC, regardless of board. For now I would try getting a better quality HDMI cable and bumping up VSOC to say 1.1V just to be sure. Monitor minimum values for VSOC in HWInfo to make sure it's not dipping too much (0.05V+).

EDC represents a limit, not the realtime current draw of anything. The fluctuations in Zentimings are also normal for APU if your performance is otherwise normal.

 

[A Computer Guy]

I think it's working as it's blacking out less as I increase VSOC.
CBr15 is working now CBr20 is still blanking out up to 1.138v.

 

[tabascosauz]

I think it's working as it's blacking out less as I increase VSOC.
CBr15 is working now CBr20 is still blanking out up to 1.138v.

Hmmmmm maybe a better HDMI cable or just switch to DP then. Didn't expect you to be at 2666, I was having blackscreens at about 4000.

Not sure why only Renoir seems to have this problem, never ran into this problem with a 5600G and 2 x 5700Gs. If Fabric or iGPU is unstable they simply crash immediately.

78C is pretty warm for a stock 4750G. My 5700G runs about that temp at 88W on a much less capable cooler.

 

[A Computer Guy]

Hmmmmm maybe a better HDMI cable or just switch to DP then.

I have a preimum 8k cable I'll try tomorrow. I've been collecting HDMI cables up to the point I realised my monitor just doesn't like 60Hz on HDMI for some reason (only when it wakes up from sleep) and shifts the 2nd half the screen down by some 30 or so pixels when it wakes up. On displayport everything just works fine at 60Hz and it couldn't be happier. It's highly annoying because my monitors only have 1 DP each but 2 HDMI and I use one of the monitors to switch between work (2xDP) and gaming (1xHDMI). If I want to switch it around and run 2xHDMI @30Hz for work and 1xDP @60Hz for gaming now I have to get adapters or DP to HDMI cables or a real KVM that supports 2xDP @60Hz.

Didn't expect you to be at 2666, I was having blackscreens at about 4000.

In my troubleshooting I downclocked the RAM back to stock frequency 2666 to help eliminate it as a factor. I was not getting any WHEA errors either way.

Not sure why only Renoir seems to have this problem, never ran into this problem with a 5600G and 2 x 5700Gs. If Fabric or iGPU is unstable they simply crash immediately.

78C is pretty warm for a stock 4750G. My 5700G runs about that temp at 88W on a much less capable cooler.

I have a wraith stealth cooler on it at the moment. I probably used some junk Corsair paste since I was just using it for testing. I have a 212 cooler somewhere I can slap it on.

End of night observations:
- As I was working my way to VSOC 1.2v it seems my system was getting more responsive each time?
- I think my UEFI/BIOS glitched or I broke something. At some point regardless of the value entered for VSOC it's now stuck at 1v reported by HWiNFO64. I got to 1.16v in UEFI then made the jump to 1.2v (because I was getting tired and impatient ) and it started to report only 1v. Then stepped it down again gradually to 1.14v in UEFI but still it only reports 1v VSOC.

 

[tabascosauz]

Are you at 4K? Most of the blackscreens I have gotten are on a 4K TV. My HDMI cables are all gronk quality so that's probably why, it's my DP cables that are all VESA certified 1.4.

BIOS shenanigans......clear CMOS is your friend. If that fails to do the trick then reflash BIOS. You should get used to doing both when spending a lot of time doing trial and error in BIOS

I am also in the process of rebuilding my 4650G, it seems to me that there is a lot about these CPUs that is not well understood. Renoir used to be OEM only so you had to look for them, and by the time they became not-OEM they were old and no one cared about them anymore. Cezanne seems to be better understood.

 

[Calenhad]

Weird how the HDMI output would flake out when under 100% load. Almost like it runs out of memory bandwidth and is unable to update the display output. But then DP should not work either. In theory it could be a HDCP problem. The output will go black if that secure connection is lost momentarily.

And don't work at 30Hz, your eyes will hate you.

Are you at 4K? Most of the blackscreens I have gotten are on a 4K TV. My HDMI cables are all gronk quality so that's probably why, it's my DP cables that are all VESA certified 1.4.

BIOS shenanigans......clear CMOS is your friend. If that fails to do the trick then reflash BIOS. You should get used to doing both when spending a lot of time doing trial and error in BIOS

I am also in the process of rebuilding my 4650G, it seems to me that there is a lot about these CPUs that is not well understood. Renoir used to be OEM only so you had to look for them, and by the time they became not-OEM they were old and no one cared about them anymore. Cezanne seems to be better understood.

The iGPU part (and I/O) of Cezanne is claimed to be the same as Renoir though. What was changed are the CPU cores. But an issue like this could possibly be fixed with a minor correction somewhere

 

[A Computer Guy]

Are you at 4K? Most of the blackscreens I have gotten are on a 4K TV. My HDMI cables are all gronk quality so that's probably why, it's my DP cables that are all VESA certified 1.4.

Using 4K monitor at 1080p for this testing.

BIOS shenanigans......clear CMOS is your friend. If that fails to do the trick then reflash BIOS. You should get used to doing both when spending a lot of time doing trial and error in BIOS

Resetting to BIOS defaults and reapplying the voltage fixed it and a few test runs went without a problem at VSOC 1.2v. Then I re-OC'ed the ram w/ DRAM@1.35v and the VSOC voltage again pegged at 1v again. BIOS shenanigans indeed.

I am also in the process of rebuilding my 4650G, it seems to me that there is a lot about these CPUs that is not well understood. Renoir used to be OEM only so you had to look for them, and by the time they became not-OEM they were old and no one cared about them anymore. Cezanne seems to be better understood.

Yea I see some interesting UEFI options show up. Have no idea what they do yet.


I'll be retesting sometime today with another HDMI cable and a different monitor too.

 

[Assimilator]

If it works over DP, why not just use DP?

 

[A Computer Guy]

If it works over DP, why not just use DP?

Limited inputs on my monitors. Each only has 1xDP and 2xHDMI. My work PC already uses the DP on each monitor and I share the monitors among the PC's (Gaming, Work, Test bench).

 

[Assimilator]

Limited inputs on my monitors. Each only has 1xDP and 2xHDMI. My work PC already uses the DP on each monitor and I share the monitors among the PC's (Gaming, Work, Test bench).

Gotcha 100%, I have the same problem.

 

[A Computer Guy]

Gotcha 100%, I have the same problem.

I had considered getting a dual monitor DP based KVM but I wasn't sure if that was going to be problematic for gaming even at 60Hz.

 

[Assimilator]

I had considered getting a dual monitor DP based KVM but I wasn't sure if that was going to be problematic for gaming even at 60Hz.

I have used multiple DP and HDMI KVMs on my 60Hz setup and only had problems with the HDMI ones dropping out randomly, the DP models never dropped a frame. Your experience here also seems to confirm that DP is the more robust of the two.

 

[datnoz]

Never got any problems with my 4650g even with torture-like oc

 

[tabascosauz]

Never got any problems with my 4650g even with torture-like oc

What qualifies as torture-like OC? This is for iGPU only.

 

[datnoz]

What qualifies as torture-like OC? This is for iGPU only.

1.6125 v on igpu @ 2.1 ghz, 90 to 95 c ( not hotspot) and 3000 mhz ram oc to3200 mhz still running good without probleme ( appart for temp) and without frequency drop not even artefacts
i use the inclueded box cooler

 

[tabascosauz]

1.6125 v on igpu @ 2.1 ghz

1.6V VSOC for 1600 fclk and 2100 vega? lol

There's no frequency drop, there is no dynamic clock or dynamic VDDCR_GFX for iGPU OC. What you set is what you get, unless you use GPU CO which is not available on Renoir

I have used multiple DP and HDMI KVMs on my 60Hz setup and only had problems with the HDMI ones dropping out randomly, the DP models never dropped a frame. Your experience here also seems to confirm that DP is the more robust of the two.

I have a similar experience with HDMI, just all around a bit more temperamental than DP

The iGPU part (and I/O) of Cezanne is claimed to be the same as Renoir though. What was changed are the CPU cores. But an issue like this could possibly be fixed with a minor correction somewhere

I/O and fabric in general didn't change much from Renoir to Cezanne but the floorplan did get reshuffled a bit around Vega 8. Who knows exactly what under the hood stuff changed. N7 process visibly improved significantly between Matisse/Renoir and Vermeer/Cezanne, regardless of whether AMD moved to 7P/7+ as rumored or just stayed on 7FF.

 

[A Computer Guy]

Update.

Testing stock with a 1080p monitor with HDMI worked with all my HDMI cables I was previously using. So it's some issue with the iGPU and my 4k monitor.
Adjusting VSOC ultimately didn't resolve the issue but did reduce it.

Also I found something interesting in that when I OC the ram the Fatal1ty X470 Gaming-ITX/ac UEFI/BIOS then ignores manual VSOC voltage settings with this CPU!

My best bet for now is to use DisplayPort with my 4K monitors. In the future I'll have to get better monitors.

For now I went and got this KVM switch and it works fine and the passthrough recognizes 60Hz.

https://www.amazon.com/dp/B09SHCDLJR