I used a program called CoreCtrl. I don’t think it’s in any distribution repositories, but you can install it from source, which doesn’t take too long. Though, you will need to add a special boot parameter to your GRUB file.
So far, I’ve really only tested my VRAM overclock in the *Nova: Covert Ops” expansion pack StarCraft II, but I’ve noticed that the cutscenes run a lot smoother. Before, there were a few that were a bit choppy, but now, they’re buttery-smooth!
No problem! It’s kinda funny that you mention that it’s in Debian Sid. I was running Debian Bookworm when I installed CoreCtrl and I actually installed from source.