This sounds like an overheating problem. Have you checked your CPU/GPU temps? 30% processor load doesn’t say any. If one of the cores that Aximmetry or Unreal uses are running at 100% you will see dropped frames. Real-time engines like Aximmetry and Unreal don’t scale performance across multiple cores linearly. This is why single core clock speeds are important and that 30% number doesn’t tell us anything about that.

Genlock doesn’t have anything to do with performance. You’re not genlocking Aximmetry with the Ref in on the Decklink. You’re genlocking the frame buffer output of the Decklink, after Aximmetry has sent the frames to the card. Genlock is not fundamental and most often just an error source. Aximmetry genlocks to the camera signal and the Decklink will output smooth frames without it. Your video mixer will (if it’s not ancient) re-clock the input signals anyway, so the only thing you really gain with genlock is avoid that re-clock, which will save you a frame or so of system latency. 

We run Aximmetry for hour each day and haven’t seen this issue, so it’s definitely not a common issue, 

Thank you for your quick reply and suggestions.

1. Regarding Overheating: I have been monitoring this closely, and I can confirm it is not an overheating problem. The GPU temperature is stable at a very low 40-45°C constantly. More importantly, if I simply close and restart the Aximmetry software (not the PC), the sync is instantly perfect again for another 1.5-2 hours. This strongly indicates a software state or buffer/leak issue, not a thermal one.

2. Clarification of Use-Case (This is the most important point): I must clarify my workflow, as I am not using Aximmetry for Virtual Studio or AR.

• I am not feeding any camera signal into Aximmetry.

• I am using Aximmetry SE purely as a real-time broadcast graphics (CG) engine, like a Chyron or Vizrt, to generate infographics.

• My project outputs a Fill + Key signal via the Blackmagic Duo 2 to a professional HD production switcher in our broadcast truck.

• The director then keys this graphic over the live camera feed inside the switcher.

The Symptom: This is why the Fill-to-Key sync is so critical. After 1.5-2 hours, the Key signal starts to lag behind the Fill signal. This results in the visual errors we see: black outlines, ghosting, and halos around our lower-thirds, logos, and animations, because the key "hole" is no longer perfectly aligned with the fill "video".

Given this context—that I am using it as a pure CG for Fill+Key, and that a simple software restart temporarily fixes it—this issue does not seem related to camera sync or hardware bottlenecks (especially at 40°C).

What could cause this performance degradation over time specifically in a non-VS, non-AR, pure Fill+Key workflow?

Thank you for any further ideas.

Hi,

GPU overheating is just one of the many possible performance issues. You are just as likely to be CPU-bound as you are to be GPU-bound. What Johan was referring to is that in Aximmetry, you don't actually see the individual loads on each CPU core. Instead, in Windows Task Manager, you can  enable the Logical processors view for the CPU performance meter to see the load on individual cores:
Additionally, even on the GPU page of Task Manager, there are various load categories besides "3D" that might get overloaded, for example, video encoding or capture card activities. These may not be indicated in the main performance meter or in the reported temperature of the graphics card.

Regarding your comment about the key signal lagging behind the fill signal: this symptom often points to a genlock issue. Are you certain the visuals generated by Aximmetry are also lagging, rather than just the video input itself? Also, have you checked whether anything is displayed in red in the ProcessorLoad panel of Aximmetry when the lagging starts?

One trick you can try is to avoid restarting Aximmetry completely, and instead toggle the video input and/or output off and then back on within Aximmetry. For example, if you are using a Camera Compound, try turning the power button off and on in the Input panel. If you are using the Video Input module in the Flow Editor, try switching the Open pin off and then back on. Whether or not these steps have any effect can help us further pinpoint the issue.

We have performed many long-duration stability tests with Aximmetry 2025.3.0 for various reasons and did not encounter issues similar to yours. We recommend updating to at least Aximmetry 2025.3.0 and testing your setup with that version. Note that you can have multiple versions of Aximmetry installed on your system simultaneously.

Warmest regards,