I got some HP x4 +R discs (Mitsubishi Chemical). Smartburn says it is 8x. I went ahead with 8x, and it burned through, but the last 20% of the disc was unreadable (PO around 100, vs 0.5 for the first 80%). I then tried 4x and the burn was successful.
Is smartburn smart? Or maybe the drive is subpar in terms of quality and cannot handle 8x reliably? (real 811S, HS0K)