Are you saying you have it with non-bidirectional but not with bidirectional?
Do you have a scanning offset adjustment configured in any of these cases?
Yes it is with non-bidirectional. 
The bidirectional have the offset adjustments set, otherwise it is bad.
But for the non-bi it doesn’t matter if i have scanning offset adjustments set or not.
So no matter what you do you cannot correct the offset when using non-bi?
That seems odd.
I’m curious if you’re potentially experiencing an issue with “PWM Rising Edge Valid”.
Take a look at this:
Configuring A Ruida - LightBurn Software Documentation
So i just changed the drivers for some noname and its ok. So i cant recommend OMC drivers at all.
Or at least the version i have.
I have another problem see the photo.
I’m getting deeper engraving when laser start firing.
This is with 1200mm/s and 50000accel.
Video: https://k00.fr/nuh3xhrc
Not sure what that might be.
What were the power settings?
Are you certain your laser head actually reaches these speeds? Does this change at other power and speed settings or is this consistent?
Its quite fast, but 1200mm/s it should reach only for 1mm in middle 
Im guessing that LPS can be too slow for this.
I will try other speeds.
I can see from the video that with overscan the machine is running wider than the burn area so I’d expect the head to reach max speed for a longer duration than just 1mm.
However, if the machine is incapable of that speed or if your maximum speed in the controller is lower than that speed it won’t be able to ever achieve those speeds. I’m not sure what’s causing the uneven burning so want to make sure I understand the issue in case that’s a factor in root cause.
You are right with overscan it can reach the speed for longer duration.
Firmware limits are higher 2000mm/s and 100000mm/s2
If you can, try taking a high speed video of the laser head with either a ruler setup or doing a long burn. Then review the video to determine start and end times of the burn and determine speed based on distance travelled.
The only thing I can think of is that the laser is starting with higher power anticipating that the laser head is moving faster than it actually gets to but then tapers off when those speeds aren’t actually hit. But I’m just speculating.
Speed is real. And it looks like PSU for laser is “slow”
Interesting. So does the problem go away at slower speeds?
And LPS is slow on power-on or power-off?
The problem go away when the max power is below 25%, not affected by speed.
When i try with older LPS same type HY-DY13, its much better, on every power settings.