I removed the mod and the flickering stopped, so I think this mod is causing it.

EDIT: It seems to happen when I open the inventory. After closing the inventory it still flickers.

Eh, I've been trying to fix that one for months. Problem is that it seems mostly random, so I can't even confirm if that's something in OpenBlocks.

I've noticed the problem with flickering too. The information might already be known to you but it's related to mipmapping. If you turn off mipmaps it removes the "flicker".

So I went a little further and discovered that the problem only occurs when the snow golem trophy appears on screen.

Hopefully that helps.

Thank you, it was indeed helpful and I was able to fix that issue.