The "sparkles" are exactly what you get when you use an HDMI cable that isn't up to the task. Be it because of a defect, or just too long for the design. (Go even farther out of spec, and you won't get a picture at all, because the initial handshake fails.)
All HDMI cables are not equal. But if the one you're using delivers a sparkle-free picture, that's as good as it's going to get.