My favorite Gigabyte user quote: "My GA-XX-XXX-XX is AWESOME Best board I ever used, I can't wait till it comes back from RMA."
Not knocking them, just I have seen that a few times and always laugh :)
Glitch in the task manager? That is unusual..
Have you changed anything in msconfig? You can limit the number of cores in there...which is seperate from actual Hardware detection I believe.
SB is a nice upgrade actually, efficiency wise and feature wise (sata 6Gbps on ich10r ;) just for one...)
Having a X58 and selling it for SB is not a good move though... IMHO X58 is still a very powerful platform. Should have taken the 980X though over the 970 ;)