Upgrade Pc Tips for Cubase 7 in windows 8


I did the upgrade for cubase 7 and windows 8 64bit.
I use also SSD disks, and when I have 6-8 instrument tracks I can hear some clicks and sometimes midi dont sound as expected… Seems that I am asking to much to the computer. I need to refer that I use East West Hollywood Strings and brass strings. and audio card Buffer of my C2+ is in MAX.
I believe I need to do an Upgrade. But I really need to know for sure.
Is my sound card weak for this job? ( for USB 2.0 ? or firewire?) Do I have to change,it? If yes What sound card you recommend?
Should I do an upgrade of motherboard and processor?
I was thinking for an AMD FX 8350. What do you think?
What is the recommended chipset for the motherboard? Is AMD 990X ok?
I need a system to work with instrument tracks for Ochestral soundtracks
I should work with 30 Instrument tracks (Hollywood Strings, Symphobia, etc…)
Just need 1 line in to record voices and guitars