Question VRAM clock of my rtx 2060 never seems to change. Is this normal?

Jul 27, 2019
I bought my computer in the end of June and after about 2 weeks, SUDDENLY my computer got awful graphic performance decrease. In all games I can't see decent anti-aliasing and games have poor shadow draw distance etc... exactly as in this video. (Sorry for my English)

So I did a test playing GTA5 for about 10~20 minutes monitoring with HWmonitor. And here's the result.
(first value=current value, second value=minimum value, third value=maximum value)

While every value looks fine, vram clock haven't changed even during the playing. I restarted my PC and did the same test again, but the same result. Is this normal? Or not, do you think this can be the cause of those graphic issue in all games? And what can cause this stuck vram clock problem?
(I really hope this is software issue, not hardware...)

My PC spec
CPU: Ryzen 7 2700x
Graphics card: RTX 2060
Mainboard: Asus tuf b450-pro gaming
PSU: Gigabyte G750H, 750w, 80 plus gold
RAM: Crucial ballistix tactical tracer 32GB(16*2), ddr4, 2666mhz
Monitor: LG 29wk600, 2560*1080 resolution, 60hz
Using SSD for everthing, Windows 10 Home 64bit