hi ! so i have a GTX 670, i7 3970X ssd's, 32Go ram, etc
some good stuff so my problem don't come from a power issue.
i have installed several nvidia's driver, didn't help, reinstalled java, minecraft, diferente shader pack, every time it's the same, it don't come form the texture pack as it does it with every one, even de default one, it don't come from optifine's shader because, as anything else, i tried every alternative and didn't help at all. i tried several shader, and as soon as they are sun light ray, i get this bug. please help =)
here are some screenshot for you to see the problem