SDI Output latency

I’m currently testing latency in a Quadro RTX4000, Quadro Sync, AJA Corvid 44, and Blackmagic DeckLink 8K Pro environment.
I have sync signals on all Quadro, Corvid, and DeckLink, but the difference between the frames shown on the display and the frames of the video output from SDI is not constant.
When I observe it, the delay can be 1-2 frames larger.
What is the solution to keep the delay constant?

I have the same phenomenon with both DeckLink and Corvid. If anything, Corvid is more stable.

I may be mistaken. If I see it without the switcher, there appears to be no delay.

The only thing the Reference Sync signals gives you is a guarantee the refresh interval for the Displayport displays and the SDI output are in ‘phase’ with each other. It doesn’t offer anything to sync-up the ‘content’ being sent out. The Windows display system, Blackmagic and AJA outputs all have their own queuing system that involve some frame delay, and there isn’t really any way to make those work in sync.

It makes sense the Corvid is the most stable, as we control that one the tightest when using GPU Direct.

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Okay, I see.
I think I will buy Corvid.

Thanks malcolm.