https://bugs.freedesktop.org/show_bug.cgi?id=102646
--- Comment #112 from tempel.julian@gmail.com --- (In reply to magist3r from comment #111)
It's not caused by my patch. Try to disable overdrive mask, revert the patch and you will see the same behavior.
There is dynamic VRAM clocking enabled by default for 1440p 75Hz also without overdrive mask. I haven't tested without overdrive mask and with your patch at the same time, but it should still change clocks regardless.