Yeah you get pretty close to the rated values. Did you try unchecking the first cache option as well? I read that SSD cache is useless so it is arguable that disabling cache will possibly improve performance?
BTW i'm having some weird issues with my SSD-mobo combo so i guess i'm done with tweaking stuff on my side...
No that WILL definitly slow things up im 100 percent certain.
What issues are you having?