Samsung odyssey G7 CRU Hz issue

[CfYz]

Can I bring up this for one question? :)
I have not the same issue with Odyssey G7 240Hz (1440p, supports 8/10bit, HDR, FreeSync), but I think one more topic isn't needed here. I'm trying to achieve Memory Idle State for higher refresh rates on AMD 24.1.1 6000 series. Cable I using is DP8k, so it's HBR3, DP standard is 1.4 on 6000 series and G7.

So :) By default monitor has 60/120/144/240 Hz refresh rates at 1440p - first three (and some 1080p) modes in standard block and 240Hz one is in DisplayID, just one 240Hz resolution saved there how it's showing in the CRU. Memory Idle State works fine at 60 and 120Hz by default, so no reconfiguration is needed for it. 144 and 240 makes memory always boosts 2300MHz all the time. After searching for solution I came to CRU and Vertical Blank intervals and Video Timings Calculator. For 144Hz I made just one change in CRU - VBlank from 40 to 103 by Video Timing Calculator for CVT-RB and CVT-RBv2 standards. And my Memory Clocks immediately lowered to 6MHz from 2300MHz. And this change works in every mode 8-bit, 10-bit, RGB 4:4:4, YCbCr 4:4:4 or HDR in any combination. And with FreeSync enabled or disabled of course.

Now with 240Hz things started to be when I need help with. According to Video Timings Calculator I need a VBlank 179. Theoretically when using 8-bit color and HBR3 cable - 179 is fine, because bandwidth is below maximum limit for HBR3, for 10-bit there's need to be DSC enabled, Wiki says uncompressed Hz for 1440p and HBR3 is 251 for 8-bit and 205 for 10-bit, so data cross confirms somehow. Cable pixel clock limit for HBR3 is theoretical 1080Mhz (this info I found here).

After entering VBlank 179 (default is 50) in CRU using 8-bit RGB 4:4:4 or YCbCr 4:4:4 mode I got pixel clock around 1050MHz or so (CVT-RB I suppose, not v2), but monitor just light up the LEDs and nothing happens. No 2D image, no OSD function. So I tried three different DP cables, various DP ports on GPU or G7. Results are the same, repeatable. But YCbCr 4:2:2 - works fine with 240Hz and VBlank 179 with any cable I got. This is results without FreeSync enabled. Decided to check which VBlank is possible and highest number working stable with 8-bit 4:4:4 is 164, 165 got always blinking signal (image) and artifacts, 166 stops showing image. Any number from 110 to 164 Memory Clock stays at maximum.

My question is where I hit the limitation? This is some circuit design or clock generator of G7? AMD says they can hit 480Hz at 1440p in marketing materials :) but I assume it's with DSC. Or I'm just doing everything wrong?

And one more thing if I enable FreeSync and nothing is changed in the CRU (default G7 settings) - 1440p 240Hz 8-bit, 10-bit, HDR, any 4:4:4 modes all working fine and memory clock lowers like it should. But when I disable FreeSync - always stays 2300MHz. So I'm stuck here can someone helps me out? Just point out to the right direction at max, so I would try to find solution myself. Thanks! And for reading too! :)

P.S. Not so related but one more question - how increasing VBlank number affects Input-Lag of pair GPU-monitor it's increasing or decreasing? Or stays the same? Maybe someone knows, haven't found such information.