lite on bh is112 2 buffer up and down when burn bluray

[mit78]

i have a powerfull system

i7 @ 4500mhz 

gygabyte z77 ud5h wifi

2x4gb ddr 2400mhz

gtx 780 

2 caviar black 1,5tb 

ssd samsung 830 128gb

when i burn dvd buffer stay at 98%,but when i burn bluray buffer goes up and down, and burning of  disc durring much longer then normal, aprox 1 hour per disc, disc it  ok writed.

please help me. 

thanks.

[LIGHTNING UK!]

Post the log of you burning such a disc please.

[mit78]

i change the cables with new ones, nothing work the same, couple months work fine, but now its a problem.

in device manager all its set at udma 6 , and bluray writer set udma 5